Category Archives: Human Evolution

Odd Ancient South African Human “Ancestor” Is Young

You’ve heard of Homo naledi, the strange “human ancestor” (really, a cousin) found a while back in South Africa. There were many skeletal remains in a cave, in the kind of shape you’d expect if they had crawled into the cave and died there, not much disturbed. They look enough like other members of our genus, Homo, to be called Homo, but if we assume that increase in brain size is the hallmark of our species, they seem to be an early grade.

Over the last ten years, we have come to appreciate the fact that our genus may have differentiated into multiple species that did not have a large brain after all, and Homo naledi is one of the reasons we think that. And, just as the “Hobbit” of Indonesia (flores) has recently been re-dated to be a bit older than people thought, Homo naledi is now dated to be a bit later than people may have thought.

Schematic of the Rising Star cave system. Picture: Marina Elliott/Wits University
Schematic of the Rising Star cave system. Picture: Marina Elliott/Wits University

For me, this is an “I told you so” moment. First, I understand, as do most of my colleagues (but not all), that a regular change over time in a trait in one lineage does not magically cause a parallel change in another lineage (though the co-evolution of a single trait in a similar direction along parallel lineages is certainly possible.) So, there was no reason to require that all later period hominins be like all other later period hominins in those later-emerging traits. Also, since no one has ever adequately explained what the heck our big brains are for, I don’t subscribe to the presumption that all evolution will always evolve the big brain just because our own big brains insist that they are really cool. So, a late small brained hominin in our genus but existing long after the split with us is actually somewhat expected.

Then, there is my sense of age based on the things I’ve seen in the area’s caves.

Geologist Dr Hannah Hilbert-Wolf studying difficult to reach flowstones in a small side passage in the Dinaledi Chamber. Picture: Wits University
Geologist Dr Hannah Hilbert-Wolf studying difficult to reach flowstones in a small side passage in the Dinaledi Chamber. Picture: Wits University
Some time ago, Lee Berger took me around some of the cave he had poking around in (long before this hominin was discovered) and showed me several animals that had crawled into the caves, probably looking for water during an arid period (this is already a fairly dry area). They had died in place and become mummified. In other caves, I’ve seen similar things, like a troop of baboons that somehow got into a cave with no known entrance and died, as well as bats that died in situ and mummified against the rock they died on.

On another occasion, Ron Clarke, another anthropologist working in the area, showed me the famous “Little Foot” which is a fossil that represents that mummy-to-stone transition, while mostly sitting on the surface of the floor(ish) of a very deep and inaccessible cave. Meanwhile, I’d been working with my friend and colleague Francis Thackeray, and he demonstrated to me how many of the diverse bits and pieces we find of australopithecines are actually probably part of individual skeletons, but discovered and excavated at very different times. These are creatures that got in the cave somehow, and were only somewhat disarticulated after death.

The whole “crawled into the cave” mode of entering the fossil record, and its presumed variant, “fell to one’s death in the cave” is different from the previously presumed process of “leopard kills you, drags you onto a tree branch hanging over a cave entrance and your bones fall into the cave” means of becoming a fossil. It is of course possible, even likely, that both of these processes occurred at various times and places.

Homo naledi, according to Lee Berger, may represent a third way of getting into one of these famous caves. He suggests that the hominins themselves dragged the dead bodies of each other into the caves, as a form of treatment of the dead. That is a spectacularly controversial claim, of course, since with a small brain how can you have a god, and without a god, how can you have ritual or burial? Of course, elephants treat their dead specially sometimes, and their brain is right where it is supposed to be on the famous mouse-to-elephant curve of brain size. And, I’d bet a dozen donuts that even though Homo naledi has a small brain compared to, say, yours or mine, it is probably a good measure above that comparative curve. It was a primate, after all.

left to right: Marina Elliott, Maropeng Ramalepa and Mpume Hlophe. Picture: Wits University/Wayne Crichton
left to right: Marina Elliott, Maropeng Ramalepa and Mpume Hlophe. Picture: Wits University/Wayne Crichton
But I digress in several directions, lets get to the point. The site of Rising Star Cave, South Africa, where Homo naledi was discovered, is now dated. These things are always subject to revision and updating, but for now, it seems like we have a pretty good estimate of the age of this incredible site.

The site dates to some time between about 414,000 years ago and 236,000 years ago. That means that the site overlaps with the approximate age of the earliest, probably, modern humans. Here are the details from the abstract of the paper, published this morning:

New ages for flowstone, sediments and fossil bones from the Dinaledi Chamber are presented. We combined optically stimulated luminescence dating of sediments with U-Th and palaeomagnetic analyses of flowstones to establish that all sediments containing Homo naledi fossils can be allocated to a single stratigraphic entity (sub-unit 3b), interpreted to be deposited between 236 ka and 414 ka. This result has been confirmed independently by dating three H. naledi teeth with combined U-series and electron spin resonance (US-ESR) dating. Two dating scenarios for the fossils were tested by varying the assumed levels of 222Rn loss in the encasing sediments: a maximum age scenario provides an average age for the two least altered fossil teeth of 253 +82/–70 ka, whilst a minimum age scenario yields an average age of 200 +70/–61 ka. We consider the maximum age scenario to more closely reflect conditions in the cave, and therefore, the true age of the fossils. By combining the US-ESR maximum age estimate obtained from the teeth, with the U-Th age for the oldest flowstone overlying Homo naledi fossils, we have constrained the depositional age of Homo naledi to a period between 236 ka and 335 ka. These age results demonstrate that a morphologically primitive hominin, Homo naledi, survived into the later parts of the Pleistocene in Africa, and indicate a much younger age for the Homo naledi fossils than have previously been hypothesized based on their morphology.

"Neo" skull of Homo naledi from the Lesedi Chamber. Photo credit: Wits University/John Hawks
“Neo” skull of Homo naledi from the Lesedi Chamber. Photo credit: Wits University/John Hawks
In addition to this date, it is reported that there are more fossil remains, from another cave called Lesedi Chamber. Here is the paper for that, which reports “… Further exploration led to the discovery of hominin material, now comprising 131 hominin specimens, within a second chamber, the Lesedi Chamber. The Lesedi Chamber is far separated from the Dinaledi Chamber within the Rising Star cave system, and represents a second depositional context for hominin remains. In each of three collection areas within the Lesedi Chamber, diagnostic skeletal material allows a clear attribution to H. naledi. Both adult and immature material is present. The hominin remains represent at least three individuals based upon duplication of elements, but more individuals are likely present based upon the spatial context. The most significant specimen is the near-complete cranium of a large individual, designated LES1, with an endocranial volume of approximately 610 ml and associated postcranial remains. The Lesedi Chamber skeletal sample extends our knowledge of the morphology and variation of H. naledi, and evidence of H. naledi from both recovery localities shows a consistent pattern of differentiation from other hominin species.”

Since both articles are OpenAccess, you can see them for yourself. Kudos to the authors for publishing in an OpenAccess journal.

And now, back to my original digression. One gets a sense of how landscapes and land forms develop, and while this can be misleading, it is not entirely absurd to postulate rough comparative ages for things you can see based on other things you’ve seen. I had assumed from the way they were described originally that the Rising Star hominins would not be millions of years old. Even though Bigfoot (found by Clarke) was millions of years old and essentially on the surface (of a deeply buried unfilled chamber) I guessed that over a million-year time scale, the Rising Star material would either become diagenetically inviable as fossils or buried in sediment, or both. But over hundreds of thousands of years? That was plausible to me. In fact, I figured the remains to possibly have been even younger, and if a date half the age as suggested was calculated, I would not have been surprised.

The evolution of our thinking about human evolution went through a period when we threw out all of our old conceptions about a gradual ape to human process, replacing that with a linear evolutionary pattern with things happening in what was then a surprising order, with many human traits emerging one at a time long before brains got big. There was some diversity observed then, but the next phase of our thinking involved understanding a dramatic diverstiy of pre Homo (the genus) life forms followed by the essential erasure of variation with the rise of Homo erectus and the like. Over the last decade and a half, we are now realizing that while the later members of our genus probably did cause, or at least, were associated with, a general decrease in that early diversity, later diversity arose anyway, and there were more different kinds of hominids, very different in some cases, late into our history. Word on the street is that we can expect to learn about even more diversity in coming years.


Paul HGM Dirks, Eric M Roberts, Hannah Hilbert-Wolf, Jan D Kramers, John Hawks, Anthony Dosseto, Mathieu Duval, Marina Elliott, Mary Evans, Rainer Grün, John Hellstrom, Andy IR Herries, Renaud Joannes-Boyau, Tebogo V Makhubela, Christa J Placzek, Jessie Robbins, Carl Spandler, Jelle Wiersma, Jon Woodhead, Lee R Berger. 2017. The age of Homo naledi and associated sediments in the Rising Star Cave, South Africa. May 2017. eLife.

Related books:

Almost Human: The Astonishing Tale of Homo naledi and the Discovery That Changed Our Human Story

Field Guide to the Cradle of Humankind: Sterkfontein, Swartkrans, Kromdraai & Environs World Heritage Site

From Apes to Angels: Essays in Anthropology in Honor of Phillip V. Tobias

Venomous: How the Earth’s Deadliest Creatures Mastered Biochemistry

You can read this book review, or you can just go HERE and listen to our interview with author Christie Wilcox. I promise you in advance that you will want to read her book!

But, if you want to read the book review, here it is…

Did you ever do anything that hurt, then you had to do it again and you knew it would still hurt, and you didn’t like that? Like getting your teeth cleaned, or licking a nine volt battery. OK, maybe you didn’t have to lick the nine volt battery, but you get my point.

When I was working in the Ituri Forest, in the Congo, taking a walk in the forest was one of those things. All sorts of things hurt. Your feet hurt because of jungle rot combined with sandy gritty stuff permanently indurated in your shoes. The leaves and branches you would have to move through hurt because it was early in the morning and they were cold and wet. And so on.

But one of the things that was not inevitable, but nearly daily, was being stung by a venomous beast of some kind. The most serious threat, of course, was snakes but that never happened to me. Much more common, but more common a night, was to be bitten or stung by a venomous ant. But that only happened, maybe, once a week or so. But nearly every day, if I would walk far enough in the forest (hundreds of meters) especially early in the morning, would be the venomous caterpillars.

Cute little caterpillars with some extra long furry thingies sticking out of them. When you brush against them, there is instant local pain, a bit like a bee sting (but different) followed quickly by shooting pains from the site of contact to the nearest major lymph node (usually the arm pit), followed by pain in the lymph node. The pain would eventually go away, after minutes, sometimes a bit longer. Most gentile urbane suburban or urban dwelling Americans and Europeans can go for years between envenomations. But if you are a human, or some other creature, living in certain environments, the risk of envenomation is not only constant, but the actual smaller scale, not deadly, envenomation events are a regular occurrence, and the threat of The Big One (such as a Black Mamba bite or a Cobra strike) is always there.

In Venomous: How Earth’s Deadliest Creatures Mastered Biochemistry, Chritie Wilcox explains why this is important. We tend to think of the interaction between animals, within or between species — those interactions that have to do with sexual competition, feeding, or predator avoidance — as involving tooth, nail, squiggly appendages, and all that. But these interactions also involve, very often, some sort of envenomation. Also, using venom isn’t always about stinging, paralyzing, or killing. Mosquitos use venom to make blood sucking possible, as the chemicals used to stop their host from feeling the bite, and to make it easier to suck the blood, etc., are venoms. Indeed, the parasites we know to be so commonly associated with mosquitos get into the host by hanging out with the venom, free riding with the injected biochemicals.

So, the evolution and diversification of venom and strategies of attack or defense, and other things, associated with venom co-evolved with anti-strategies to avoid the pain, paralysis, to avoid the bite or sting or brush of the venomous hair of the caterpillar. Indeed, understanding the evolutionary history and patterns of adaptation associated with the use of venom is just as good as any syndrome of interaction or behavior for the study of how evolution itself works.

Christie Wilcox’s book is one of the better science books I’ve read in some time. This is an area I should know something about, as a biological scientist, and as a person who has lived for years in the venom-rich rain forest. But I still found myself learning something new with every page turn. Wilcox has studied venom for years — this is her area of specialty — and her text is enriched with well placed and well told stories of her own sometimes harrowing experiences.

The book is very well written and very well documented with copious notes.

A fascinating subtext has to do with human evolution and experience. There is a theory that primates generally are tuned to venomous creatures, especially snakes, and some of the key primate evolutionary adaptations are shaped by the experience of living in trees where large venomous snakes hunt. In the present day, there is what looks to me almost like a cult of self envenomation, found among people who keep venomous snakes (mainly), who inject themselves with venom regularly in order to stay, maybe, immune in case of an accidental bite. But they seem to be doing something more than this, almost using the venom as a sort of drug or, fascinatingly, as an elixir to extend life. On top of this, there is even an expanding practice of using snake bites, or ingesting the powdered form of snake venom, as a recreational drug. This set of not too unrelated human stories sits intriguingly amid myriad stories of venom use among a wide range of animals, including several mammals, fish, cone snails, snakes and lizards, etc.

I get the impression that bad scientific knowledge (generally older), folk stories, and meemish yammering about venom is among the most widespread form of falsehood in our parascientific discourse. As I read this book, I remembered may instances of hearing or reading this or that thing about this or that venomous animal, or category of animal, that turned out wrong as more recent science exposed what was really happening. For many years, scientists were not sure if the platypus was venomous (it is) or why (it is all about sex for them). How does the Komodo Dragon kill large prey such as the Water Buffalo? If you look it up, you may find out that the Komodo Dragon maintains a bacterial flora in its mouth that causes necrosis in a bite victim. That is not true. Read Christie Wilcox’s book to find out the real story! And so on.

Venomous: How Earth’s Deadliest Creatures Mastered Biochemistry is out in August, but available for pre order.

Mike Haubrich and I interviewed Christie on the Ikonokast podcast, and it turns out to have been a fantastic interview. Listen to it here!

Christie Wilcox blogs at Science Sushi.

Why I would believe in God if I wasn’t an atheist.

I have often made the argument that religiosity, a personal belief in god, spirits, the supernatural, etc., would emerge in human societies on its own if it wasn’t there already.

Imagine taking an entire generation of people in a geographically isolated region, and wiping out their memory of religion, and also, removing all references to religion that they might ever encounter. They would be religion free for a while, maybe even for a number of generations, but eventually, they would reinvent it.

Everybody has a theory of why religion exists, what purposes it serves, etc. etc. Until proven otherwise, I will assume that these “functions” are all post hoc. Religion may serve one or another role in a given society or culture, but I’m going to assume that religion was incorporated for this purpose after the fact, not developed, evolved, or inserted for this purpose. I may be wrong, but until I see compelling evidence to the contrary, I think it is the safest assumption.

Why would religion (using that term very loosely) emerge in a non-religious human society? Because of lawnmowers and dogs, or dreams or delusion, mainly.

One day I was driving down the street and I witnessed a dog transform into a law mower. How could that happen if there was no spirit like force beyond some kind of veil that usually clouds our perceptions, hiding from us things that defy physics most, but not all, of the time? The only way to explain this is to invoke some sort of religious thinking, right?

Here’s what happened. It was a bright sunny fall day. Warm. It was a densely populated residential neighborhood. Families were out, parents raking leaves and the kids jumping in them, dogs running around, children playing ball. I was unsure of where I was or where I was going (I was not familiar with the neighborhood), scanning back and forth for street signs and house numbers. The sun was low enough to be causing a lot of glare. So, I was paying a lot of attention to my peripheral vision (looking for a kid running into the street, or a dog not seeing me coming). Off to my left, I saw a large dog sitting on a lawn. I glanced to the right, then back to the left, and now saw that the dog was a lawn mower with someone’s coat draped over the handle. Miraculous transformation of a spirt being!

Or, a simple mistake.

And that, of course, is how I would actually explain what I say … a trick of the lousy light in a confused tapestry of activity that I was not initially paying much attention to.

We experience things in real life that can’t be true, now and then. We usually but not always explain them, but sometimes we explain them with “I don’t know what that was, but it is not important… just a trick of the light.” But say I was a young and impressionable youth searching for meaning in life, and I had just seen a talk given by a spiritualist who claimed that spirit dogs occasionally appeared out of nowhere, transforming from inanimate objects into a large dog, then back again. Well, if that has been the case that day, perhaps I would have started worshiping spirt dogs, and I would never look at a lawn mower quite the same way again. If the spirit dog belief was a growing belief in my subculture, a belief held by community leaders, respected individuals, potential mates, and family members, I might be even more likely to break that way. And so on. You get the point.

The current National Geographic Roundtable asks the question, “Is belief in God innate in our brains, as if it were installed by some divine programmer? Or is spirituality a more complex evolving adaptation that has both helped and harmed us as a species?”

Neither, as stated. It is not innate in our species, as people usually understand the term — coded for by genes, the inevitable outcome of typical development. But I said it would always emerge in human societies, right? Yes, but not because it is innate (built in) but because the process of human behavior in the context of our physical world and culture would prod and poke and hint and push until it started to emerge here and there, and eventually, it would become part of the larger system of behavior. And no, of course, a tendency to eventually develop religion in a society was not put there by a divine programmer, any more than a paisley tea pot was set into orbit around the Planet Jupiter by a mischievous flying unicorn.

Yes, religion, spirituality, and all that, is a complex changing thing that may have helped and may have harmed. But is it an adaptation? No. It is a side effect.

That’s my story and I’m sticking to it. But to get a different set of perspectives, check out The God Brain, which premiers Feb 21st at 9PM Eastern on National Geographic.

Host Jason Silva travels to Jerusalem, Israel, to explore, “The God Brain.” Fascinating new research has uncovered the possibility that believing in God may be hardwired in our brains. Is this because a divine power greater than us installed this software? Or is it possible that the believing part of the brain has evolved over thousands of years as an evolutionary adaptation that helps us succeed as a species. Physician and neuroscientist Andrew Newberg of Jefferson University Hospital has spent decades exploring the neurophysiology of religious and spiritual practice. Dr. Trevor Cox from the University of Salford, an expert on sound perception, explains how you respond to different musical keys and music played in churches. Dr. Jennifer Whitson of UCLA focuses on the psychological experience of control and sheds light on how to make sense of the environment and inexplicable events. Dr. Bruce Hood, an experimental psychologist at the University of Bristol, will demonstrate that even the most nonbelieving brain can have unconscious biases, which are fundamental characteristics for supernatural thinking.

How Dogs Won The World

Years ago I proposed a theory (not anywhere in print, just in seminars and talks) that went roughly like this. Humans hunt. Dogs hunt. Prey animals get hunted. Each species (or set of species) has a number of characteristics such as the ability to stalk, track, kill, run away, form herds, etc. Now imagine a landscape with humans, wolves, and game animals all carrying out these behaviors, facilitated with various physical traits. Then, go back to the drawing board and redesign the system.

The hunting abilities of humans and dogs, the tendency of game animals to herd up or take other actions to avoid predation, etc., if disassembled and reassembled with the same actors playing somewhat different roles, give you a sheep herder, a protecting breed of dogs (like the Great Pyrenees or other mastiff type breeds), a herding dog (like a border collie) and a bunch of sheep, cattle, or goats.

Even human hunting with dogs (not herding domesticated animals) involves a reorganization of tasks and abilities, all present in non-dog-owning human ancestors and wolves (dog ancestors), but where the game are, as far as we know, unchanged. Human hunters documented in the ethnographic record, all around the world, had or have dogs, and those dogs are essential for many hunting types. The Efe Pygmies, with whom I lived in the Congo for a time, use dogs in their group hunting, where they spook animals into view for killing by archers, or drive them into nets that slow the game down long enough to be killed. The Efe actually get a lot of their game by ambush hunting, where a solitary man waits in a tree for a game animal to visit a nearby food source. He shoots the animal from the tree with an arrow. But, even then, the dog plays a role, because the wounded animal runs away. The trick to successful ambush hunting is to do it fairly near camp so you can call for help when an animal is wounded. Someone sends out a dog, and the dog runs the animal to ground. And so forth.

Scientist and science writer Pat Shipman has proposed another important element that addresses a key question in human evolution. Neanderthals, who were pretty much human like we are in most respect, and our own subspecies (or species, of you like) coexisted, but the Neanderthals were probably better adapted to the cooler European and West Asian environment they lived in. But, humans outcompeted them, or at least, replaced them, in this region very quickly once they arrived. Shipman suggests that it was the emerging dog-human association, with humans domesticating wolves, that allowed this to work. Most remarkably, and either very insightfully or totally fancifully (depending on where the data eventually lead), Shipman suggests that is was the unique human ability to communicate with their gaze that allowed this to happen, or at least, facilitated the human-dog relationship to make it really work. We don’t know if Neanderthals had this ability or not, but humans do and are unique among primates. We have whites around our Irises, which allow others to see what we are looking at, looking for, and looking like. We can and do communicate quite effectively, and by the way generally viscerally and honestly, with our glance. This, Shipman proposes, could have been the key bit of glue (or lubricant?) that made the human-dog cooperation happen, or at least, rise to a remarkable level.

The Invaders: How humans and their dogs drove Neanderthals to extinction, by Pat Shipman, outlines this theory. But that is only part of this new book. Shipman also provides a totally up to date and extremely readable, and enjoyable, overview of Neanderthal and contemporary modern human evolution. Shipman incorporates the vast evidence from archaeology, physical anthropology, and genetics to do so, and her book may be the best current source for all of this.

This is a fantastic book, and I highly recommend it. Shipman also wrote “The Animal Connection,” “The Evolution of Racism,” “The Wisdom of the Bones: In Search of Human Origins,” and several other excellent books on human evolution and other topics. Shipman, prior to becoming mainly a science writer, pioneered work in the science of Taphonomy, developing methods for analyzing marks on bones recovered from archaeological and paleontologic sites, such as those marks that may have been left by early hominins using stone tools to butcher animals.

Seriously, go read The Invaders: How humans and their dogs drove Neanderthals to extinction.

Micro-Evolution In Greenland: Inuit Diet, Weight, and Stature

There is a new paper in Science linking genetic variation in people living in Greenland with long term selection for managing a marine-oriented diet, affecting stature, weight, and probably, physiological processing of omega-3 polyunsaturated fatty acids (PUFAs).

The vast majority of the variation we seen in stature (height) among humans is not genetic. That is a fact hard to swallow by so many of us who were told in biology class that “height is a complex genetic trait with many genes affecting it.” It also seems wrong because the classic examples of variation in stature, the Pygmies of Central Africa (short) and the Maasai of East Africa (tall) are assumed to be populations under selection that caused them to be outliers. Of course, the Maasai are really not that tall by modern Western standards, but the story about them being tall, first told by relatively short European travelers who met them in the 19th century, persists, despite the fact that those travelers’ offspring, such as Modern Americans and Brits, are in many cases significantly taller than their own ancestors without natural selection being the cause.

But there are some genetic factors that control height and weight and account for some percentage of variation in those phenotypes. Pygmies taken from their homeland and raised among people with unlimited food supply do not grow tall. They may become obese, but not tall, because one of the main genes that regulates growth in almost all humans simply does not function in Pygmies. (One individual Efe Pygmy I’ve met who was raised among Italian nuns, in Italy, was short but rather wide.) There may be other short statured populations with a similar genetically determined stature. But as far as we can tell, something like 20% (and that is probably an overestimate) of variation in stature in living humans over the last century or so can be accounted for by genetic variation. The rest is a combination of diet and, I suspect, an epigenetic effect linked to maternal size and diet. When a population of relatively short people get unlimited food the next generation is taller. But then, the next generation is taller still. It is as though mothers won’t give birth to maximally sized offspring, just somewhat larger offspring, who then give birth to somewhat larger offspring, so the part of the demographic transition where everyone gets taller happens over a few generations. This is a well documented but not very well explained phenomenon, and the explanation I suggest here is merely a hypothesis.

A new study in Science looks at the Inuit people, and some Europeans living in the same place they live, in this case Greenland, and finds a genetic component to Inuit stature and weight. There are also other differences having to do with processing elements of their relatively unusual diet.

The key result with respect to weight and height is shown in the graph at the top of the post. The letters (GG, GT, TT) are the alleles (T is the derived allele). Homozygotes for the derived allele are quite a bit less massive, and a small amount shorter, than those without the allele, and heterozygotes are in between.

Here is the abstract from the paper:

The indigenous people of Greenland, the Inuit, have lived for a long time in the extreme conditions of the Arctic, including low annual temperatures, and with a specialized diet rich in protein and fatty acids, particularly omega-3 polyunsaturated fatty acids (PUFAs). A scan of Inuit genomes for signatures of adaptation revealed signals at several loci, with the strongest signal located in a cluster of fatty acid desaturases that determine PUFA levels. The selected alleles are associated with multiple metabolic and anthropometric phenotypes and have large effect sizes for weight and height, with the effect on height replicated in Europeans. By analyzing membrane lipids, we found that the selected alleles modulate fatty acid composition, which may affect the regulation of growth hormones. Thus, the Inuit have genetic and physiological adaptations to a diet rich in PUFAs.

How long have the Inuit been living this lifeway, in this environment? Actually, not that long. The researchers, in their supplemental information, suggest that it could be as long as 30,000 years, but this is unlikely, or at least, the story is more complicated.

There are several complications to understanding the history of the selective environment of the Inuit, the environment that would have shaped this genetic adaptation. First, the environment has changed. Not only have we gone from an ice age to no ice age during this 30,000 year time period, but with sea level rise during the Holocene, the ecology of the arctic has changed considerably. Large areas of the continent have been inundated by the sea. Prior to that, most of the ocean adjoining land was immediately deep. With the inundation of the continent, vast relatively shallow areas of ocean would exist. Nutrients well up along the continental shelf, but shallow areas are also potentially nutrient rich because of sediments coming off shore. During glacial melt periods, there may have been frequent large scale fresh water incursions which would have had occasional disastrous effects on the local ecology. The position of estuarine settings, which can be very productive, would change. As sea level rise slowed, near shore sediments may have had a chance to build up, causing regional increases in productivity.

The migratory patterns, overall distribution, and abundance of marine mammals and common shoaling fish would have changed dramatically, and multiple times, during the last several thousand years. It would not have been until about five thousand years ago that things would have settled down allowing long term regional foraging adaptations to emerge. Prior to that there may have been periods when the marine environment was significantly more, or significantly less, productive.

Meanwhile, the ancestors of the Inuit themselves moved a great deal during this period. They were not in Greenland, or anywhere in North America, 30,000 years ago, but rather, in an unknown location in Asia. The Inuit ancestors were part of a later migration into the New World. The association (population wise) of true Arctic people and others living farther south is not known.

A second factor is cultural adaptation. When we look at the traditional Inuit foraging patterns and associated technology, together with the preceding prehistoric Thule adaptations, we can’t help but to be impressed with the highly specialized effective approaches, both strategically and technologically, to acquiring marine resources. Boats, lamps, harpoons, and processing tools are highly refined and efficient. That material culture and strategic approach, however, is only a few thousand years old. Before that, in the region, were the Dorset, who simply lacked many of these tools. It is possible that the Thule and Inuit had sled and sled dogs, but earlier people in the Arctic did not. And so on. The ancestors of the Inuit, just a few thousand years ago, could not have had as specialized a diet as the traditional (modern ethnohistoric) Inuit. Cultural adaptations changing over time is as important as, if not more important than, the afore mentioned likely changes in environment.

So, I’m not going to argue that these adaptations are not 30,000 years in the making. Rather, I’ll argue that strong selection for these alleles could be as recent a few thousand years or even less, and that prior selective environments (the combination of the natural environment and human cultural adaptations to it) may have different and the situation may have been rather complicated for many years. In other words, the new, and very interesting, results looking at the Inuit genome need to be integrated with a better understanding of Inuit history, which is probably going to require a lot more research in the region.

There is a second point I want to make about this paper. We see research suggesting a genetic explanation for a lot of things, but often, in the past, that has involved finding a correlation between this or that genetic variation and a presumed phenotypic feature. Often, the next key step to establish the link isn’t, perhaps sometimes can’t be, taken. This is the link between the observed genetic variation and a good physiological story. The present research finds genetic variation associated with physiological features that seem to be associated with a marine-oriented diet in an Arctic or Sub Arctic setting. That makes this research really valuable.


Greenlandic Inuit show genetic signatures of diet and climate adaptation
Matteo Fumagalli, Ida Moltke, Niels Grarup, Fernando Racimo, Peter Bjerregaard, Marit E. Jørgensen, Thorfinn S. Korneliussen, Pascale Gerbault, Line Skotte, Allan Linneberg, Cramer Christensen, Ivan Brandslund, Torben Jørgensen, Emilia Huerta-Sánchez, Erik B. Schmidt, Oluf Pedersen, Torben Hansen, Anders Albrechtsen, and Rasmus Nielsen
Science 18 September 2015: 349 (6254), 1343-1347. [DOI:10.1126/science.aab2319]

Tales of the Ex-Apes

Jonathan Marks’ new book is called “Tales of the Ex-Apes: How We Think about Human Evolution

I’ve got to tell you that when I first saw the title of this book, the letters played in my head a bit. Tails of the Ex-Apes. That would be funny because apes don’t have tails. Or Tales of the Exapes. Pronounced as you wish. Perhaps in an Aztec accent.

Anyway…

Staley_2009_author_lJon Marks is a colleague and a friend from way back. He is a biological anthropologist who has engaged in critical study of central biological themes, such as genetics, and he’s said a few things about race. He wears black, often does not shave, and has probably been a member of the Communist Party, or at least, taught a class or two on Marxist Theory. So, a book by Marks on “how we think about human evolution” (the subtitle) is not going to be about human evolution, but how we frame questions about human evolution, and how the process of unraveling answers to these questions revel our own biases. Dialectical stuff. Like that.

In the book Jon says interesting things about basic anthropological theory, thought, and key touchstone figures and topics like Darwin and kinship. On the more biological side of things, species, adaptations, gene trees, and phylogeny. The destructive core of the book is an anti-reductionist critique of evolutionary theory and the constructive core of the book is an bio-cultural argument as it applies to doing anthropology, as well as how it applies to the human (or just prehuman?) transformation to a self considering sort of sentient being that bothers to write books about the process of asking questions about itself. Humans are a product of lived experience, but not just that. Humanness is the product of the sum of human’s cultural history. And, actually, science, which is an important human thing, does not escape that framework, something I probably agree with (^^see the subtitle of my blog^^). Marks writes,

… we see the human species culturally. Science is a process of understanding, and we understand things culturally. We hope that we can observe and transcend the cultural biases of our predecessors, but there is no non-cultural knowledge. As a graphic example, consider the plaque that was attached to Pioneer 10 … Why was NASA sending pornography into outer space? … Because they wanted to depict the man and woman in a cultureless, natural state. But surely the shaves, haircuts, and bikini waxes are cultural! As are the gendered postures, with only the man looking you straight in the eye. In a baboon, that would be a threat display; let’s hope the aliens … aren’t like baboons.

And so on. Like that. Great book.

If you are teaching a course in human evolution, you might seriously consider using this as a second reading because of the critical treatment of material surely left unexamined by your textbook. Also, it would give the students a fairer sense of what they are in for if they chose Anthropology as a major, for better or worse. This is not introductory material, but the prose would work for any college student. Also, the text is well footnoted.

The book will be out any day now, scheduled for September. Available in various formats, very much worth the read.

The significance of the new East Asian fossil human Penghu 1

A new early human fossil has been reported, recovered from the seabed near Taiwan. We are calling it Penghu 1.

Simply put, it is the lower right jaw of a hominid (hominine) that most resembles either a form of Homo erectus or Archaic Homo sapiens (kin to, but not, Neanderthal). Teeth are fairly useful for categorizing hominids into groups that can be thought of as species. This hominid does not look like modern humans (teeth are way too big and the enamel is not right). It does not look like African Homo ergaster or Asian Homo erectus. It does not look like Neanderthal or so called Denisovan. It looks most like Hexian, a middle pleistocene hominid (about a half million years old) from China, but not exactly. But close. Hexian, for it’s part, looks like earlier Homo erectus but changed over time to be distinctly different from other contemporary (late) Homo erectus from East Asia.

I’ll provide more information about the fossil below, but since the paper that reports it is available on line you might as well go read the original. Rather, I’d like to say a couple of things about the possible significance of this find.

First, this is probably a new species, though it could end up getting lumped with Hexian. But, the new fossil probably dates to the last interglacial (120,000 years go) or later. I’m guessing later if its presence on the sea floor indicates that the original possessor of the mandible lived during times of lower sea level. (I suppose this could be an individual that died and floated down a river. Or fell out of a boat!?!?!?)

Let’s assume for a moment that Penghu 1 is a new species, in the sense that we see Neanderthals, Denisovans, and various variants of Homo erectus or Archaic homo as different species (we’ll put aside species-population differences and arguments for now). If so there is one obvious very significant (provisional) conclusion that could be advanced, and a second less obvious (and more provissional).

The obvious significance is that Penghu is yet another indicator that multiple different hominids lived on the Earth at the same time after the rise of Homo erectus. We see lots of different hominids, mainly called Australopithecus, in Africa prior to about two million years ago, which is interesting but also known for some time now. But for a long time it looked like there was not too much diversity in the fossil record after that, though we’ve always seen some. Over the last couple of decades, though, the evidence for Pleistocene diversity in Eurasia appears to have grown, with Homo floresiensis and Hexian in the east, Denisova Cave in the middle, and the hominid from the Republic of Georgia in the west. The idea of a high level of diversity is not new, but it is a relatively recent concept and is growing. (I’ll also mention that finding a new hominid on the sea floor underscores the problem we have that so many of the great places for early humans to live are inundated!)

The less obvious and much more conjectural significance is in the shift of diversity from one region of the world to another. Prior to about 2.0 million years go, we see great diversity in hominids in Africa (where, for the most part, most of the hominids lived). Over time, African diversity dwindles as modern humans, or a hominid just precedent to modern humans, seems to have more or less taken over and replaced their contemporaries. Archaic hominids, however, which had already spread into Eurasia, continued the diversification earlier hominids had achieved, and this diversity was manifest in the absence of those pesky moderns.

Putting this another way, one could say that hominids, including pre- and post-Homo forms, have as one of their characteristics a propensity to diversity. This is true of many (but not all) primates. It may have to do with ecological and social/cultural characteristics of the various species, or perhaps basic demography. Adherence to ecological zones that are patchy and spread apart would encourage more speciation than might occur if populations were more connected or continuous. Related (or alternatively, depending) great increases and decreases of population size, causing separation of subgroups, might enhance this. At the same time, evolutionary stasis is repressed; separate groups change fast enough to be noted by us on time scales of several thousand years.

In contrast, modern or near-modern humans seem not to have had this propensity.

The most obvious explanation for this difference is, it seems to me, the degree of cultural buffering found in modern humans being much higher than in these other hominids.

OK, enough of the wild speculation. Here is the abstract from the paper:

Recent studies of an increasing number of hominin fossils highlight regional and chronological diversities of archaic Homo in the Pleistocene of eastern Asia. However, such a realization is still based on limited geographical occurrences mainly from Indonesia, China and Russian Altai. Here we describe a newly discovered archaic Homo mandible from Taiwan (Penghu 1), which further increases the diversity of Pleistocene Asian hominins. Penghu 1 revealed an unexpectedly late survival (younger than 450 but most likely 190–10 thousand years ago) of robust, apparently primitive dentognathic morphology in the periphery of the continent, which is unknown among the penecontemporaneous fossil records from other regions of Asia except for the mid-Middle Pleistocene Homo from Hexian, Eastern China. Such patterns of geographic trait distribution cannot be simply explained by clinal geographic variation of Homo erectus between northern China and Java, and suggests survival of multiple evolutionary lineages among archaic hominins before the arrival of modern humans in the region.

The citation and link:

Chun-Hsiang Chang, Yousuke Kaifu, Masanaru Takai, Reiko T. Kono, Rainer Grün, Shuji Matsu’ura, Les Kinsley & Liang-Kong Lin. The first archaic Homo from Taiwan. Nature Communications. 27 January 2015.

The location:
Penghu_1_Hominid_Location

And above the post is a picture of the fossil.

How to find a Leprechaun

Nature editor and author Henry Gee has produced his Christmas list in which he describes his three wishes as an editor at a scientific journal; he enumerates the scientific discoveries that sit at the top of his professional “bucket list.”

Henry Gee. Not a Leprechaun.
Henry Gee. Not a Leprechaun.
I started to write a comment on Henry’s blog post, here, but it turned into a blog post of my own, here:

Henry: As you know, I address in a fictional context in “Search for Sungudogo” (now only 99 cents on Amazon) all three of your wishes, the discovery of life elsewhere in the universe, the discovery of intelligent life somewhere, and the documentation of non-human hominids in recent times (including the present) like, but later than, the “Hobbit” at Flores. (Drop me a line for a review copy.) In the revised version of the novella I also explain the origin of Penn and Teller. But I digress.

The chance of the existence of Homo notspaiens at present must be zero, unfortunately. But I do like the idea of proto-historical or historical cases. “Like” as in how a TV detective “likes” a particular suspect for a particular crime. Maybe it is just a hunch. A re-examination of all those cases in the sepia literature of little people or not-quite-humans thought to be imagination, serious confusion, or out and out racism may be necessary.

I’d like to put a finer point on the prediction though. The hominid needs to have existed after some key point in time (which may be hard to identify on the ground but that could be fairly easily defined as an archaeological or historical transition). For example, post first writing or post settled horticulture. Flores already fits the obvious next oldest criterion of post Last Glacial Maximum (LGM). Also, and this is not a requirement but it would be way cool, I would like them to have existed at the same time as and in the same region as the Wrangle Island Mammoths because then tiny people-like creatures could have hunted, or ridden, or otherwise lived among, tiny furry elephants.

Also, I’ll offer a prediction of where the hominid would have lived. It is most likely to be in an area where the landscape has two distinct habitats that are long term and well defined. One is a habitat likely to be inhabited long term by regular humans and the other where regular humans are likely to forage or visit only now and then, but where this second, marginal, habitat is livable. Also, it is more likely at the outer edge of post-LGM expansion, and in a region where human population would not have been dense prior to the great Exchange of Horticultural Products that began in the 15th century. (In fact if I were to pick the most likely local date formula for the extinction of Homo notsapiens globally, if there were a bunch of them, it would be the introduction of yams, manioc, maize, taro, or other staple plant brought in from the other side of the planet to grow locally.) This means the Flores hominid may have chipped its last rock when cassava or corn were first planted in the region, which would be very late and easily meet your criteria. I assume people are looking vigorously.

Yes, I just described Flores, but that’s the point. Those are the characteristics that allowed for the Indonesian Leprechaun. We might look at regions covered by the last glacial ice mass, regions far to the east of Africa, dense tropical rain forest, etc.

This also predicts that stories of “the little people” (or “the big people” depending) would be distributed more commonly in a certain region of the world’s map. Like this, maybe (and roughly):

Where to look for lepruchans or big foots.
Where to look for Leprechauns or Bigfoots.

I’ve ruled out the new world simply because. Bad reason, I know. It is entirely possible that the New World was thickly inhabited by Taltos and Leprechauns, the only really solid argument against that being a complete lack of evidence…

Catching Fire. The other one.

Catching Fire is apparently a very popular book and/or movie that everyone is very excited about. But Catching Fire: How Cooking Made Us Human is a different a book about some interesting research I was involved in about the origin of our genus, Homo.

You can pick up a copy of our paper on this page. We call it “The Cooking Hypothesis.” The basic idea can be summarized with these points:

1) Cooking food transformed human ecology. Many potential foods in the environment can’t be consumed by humans (or apes in general) without cooking. But adding cooking to our species-specific technology, we can access those foods effectively transforming our ecology to a much greater extent than the vast majority of evolutionary transitions, especially single-event transitions, have ever done. The total number of calories in the natural environment that become available to an ape that can cook goes up by orders of magnitude.

2) This increase in available calories left a biological signal that is very impressive. Two major changes happened in the hominid body (in early Homo erecuts/ergaster). One is an approximate doubling in body size from an earlier Australopithecine or “Early Homo” ancestor. The other is a reduction in tooth size. Less eating equipment with a body demanding so much more in energy to grow and maintain signals a fundamental change in the food supply. There may be more than one way this could have happened, but so far adding cooking to our technology seems to be the best explanation.

3) Related, this is when we see brain size, relative to body size and in absolute terms, increase. Neural tissue is picky, expensive, and costly. Having a significant increase in brain size may be related to the demands (on the brain) of adding cooking to our behavior in that the size increase is allowed by the extra energy. And, it may be related in that the larger brain may provide the capacity to have this behavior.

4) The actual act of cooking, as a technology, may or may not demand a larger brain. But the process of cooking almost certainly involves central place foraging (bringing all the food back to one place, much of the time, to cook it) and delayed consumption (as opposed to eating the food where you find it). The basic pattern for a chimpanzee-like ancestor is to eat the food where you find it. Bringing food into close proximity to other members of your group virtually guarantees direct competition for food, which makes getting to food to begin with a highly questionable thing to do. In order for cooking to work, the social interactions typical of an ape have to be modified significantly. Cooking demanded, facilitated, and made major changes in social structure “worth it” from the point of view of natural selection.

5) These changes in social structure are probably indicated as well by changes in stone tool technology. Early cookers also were early hand-ax makers, for example. Human ancestors went from making primarily expedient, one time use, very simple stone tools to making tools that required a great deal of investment in time and energy to learn the technology, get good at it, and even for the production of individual tools (including acquisition of better than average raw materials in many cases). Once the tools were made they seem to have been used, often, for long periods of time. It is hard to imagine a chimp-like creature carrying around a tool into which she invested time and energy without it being taken away. This is an important transformation.

6) Less visible but very likely is a change in social system which could be called the rise of proto marriage. Sexual arrangements of a human-like kind are very different than for chimp. The ability to allow others to possess food or invest in more sophisticated technologies may be parallel to the ability to have more or less exclusive sexual contracts among individuals. This is indicated independently in the fossil record by a large decrease in sexual dimorphism in body size. In polygynous species like chimps males are often much larger than females, and this seems to have been the case with pre-Homo erectus/ergaster ancestors. But at the same time the body size increase and tooth size decrease happen, we also see a reduction in sexual dimorphism in body size, strongly indicating a major change in social arrangements. The best two explanations for this may be a shift to a gibbon-like pattern of paired-off monogamous adults living more or less alone, or a human-like pattern of paired-off monogamous adults living in larger social groups.

It is an idea that would have caught on. It would have selected for more nuanced communication, and may thus have facilitated the origin of what we now know of as human language and symbolic processing.

So when you are eating your Thanksgiving dinner this year, most of which will be cooked, look around at the people at the table and, briefly, imagine them to be chimps. Then go back to your meal and try to put all those thoughts aside…

Evolutionary Psychology Panel at CONvergence 2013

There is now a video and a transcript of the Evolutionary Psychology Panel at CONvergence 2013. Many of you, when you watch this, will become enraged at things said by the panelists. Rumors of what was said had already been spread around on the internet and as I understand it Jerry Coyne and Stephen Pinker have already become enraged. Or maybe the loved it. I’m not sure.

If you want me to respond to any of your enraged rage regarding anything that was said, or for that matter, if you have anything at all … negative, positive, informative, whatever … to contribute to the conversation please put it in the comments below. Of late I’ve been engaged in a handful of projects that curtail my web surfing activities so if you put comments somewhere other than below this post I’m very unlikely to ever see them. This thread will not be moderated unless you post secret launch codes or whatever. (Comments are typically held in moderation until I release them unless you are a prior-trusted commenter, but I’ll put whatever you’ve got here that is not spam … or launch codes.)

Here’s the video:

The transcript is here.