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.
A few days ago the UN agency in charge of keeping track of cancer risks listed meat and processed meats as to some degree or another likely to cause an increase in cancer risks. I wrote about that here. More recently. I was interviewed by Joshua Holland on the Politics and Reality Radio show about that story. Here is the interview for your listening pleasure:
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]
I’m thinking it will be the food you eat that gets you. Here’s why.
Humans eat a wide variety of foods; as a species, the diversity of species we eat is greater than any other animal by a very large margin, with the only quirky exception being the animals that we take along with us, the commensals such as rats and cockroaches. Most primates eat a high diversity of foods, but about two million years ago or a bit less, according to the “Cooking Hypothesis” (which a lot of people think is correct) we took an already diverse primate diet and added to it anything we might encounter in the environment that could be made edible with heat and added that to our diet. More recently, beginning about 10,000 years ago, we applied additional technology and the new practice of plant husbandry to convert other foods, some edible some not, into more useful items for our diet. Humans around the world did this independently over several thousand years, in parallel.
Then we got boats that were capable of doing magical things like sailing up wind, and navigation technologies that allowed humans to be less lost when doing so over great distances. Some humans had done this much earlier at a smaller scale, but by the 15th century there were big wooden boats criss crossing the seas, bringing people to places they had never been before, and along with them the foods people ate all over the world.
Have you looked at photographs of traditional people living in traditional, seemingly timeless, ways in places like Africa, the Amazon, or New Guinea? Look again, and focus on the things that form the backdrop for the scenes shown in those photographs. One of the things you’ll see in many pictures is the plantain, or the banana. You might notice the huge elephant ear leaves of taro plants. If you look closely you might notice cassava growing in the fields, or maize.
Maize was domesticated in Mexico, taro, plantains, and bananas in various different locations across south and southeast Asia. Cassava comes from the lowlands of South America, and potatoes come from the Andes. Some Yams come from Africa, some from South America (I oversimplify a bit). You can’t find a modern traditional diet, as it were, that does not include ingredients from continents other than where the traditional diet lives today, except perhaps in Ethiopia. Everybody eats everybody else’s food all the time. The main determinant of where food is grown is not where it was first domesticated, but rather, the limitations of seasons, rainfall, heat and cold. And even there, the limitations are relaxed. Maize only grows in the colder regions because varieties have been developed to do so, and many plants are grown in regions normally too arid for them, by virtue of irrigation.
Adding all this up – the diverse primate diet, the addition of cooked foods otherwise not edible, the artificially selected crops, and the global exchange of horticultural goods and practices – and you get a huge variety of food, the largest variety of food any species has ever managed to include in its diet. (Other than the rats and cockroaches, of course.)
Despite all this diversity, something has remained more or less the same all along. The “traditional” diet for humans, though much altered with cooking, is relatively low quality. I use the term “low quality” in the way an ecologist uses it. How many usable calories do you get out of a kilo of the food item under consideration? Or, related, how much work do you, using food preparation, chewing, and digestion (including the work done by the friendly microbes living in your gut) to convert that kilo of food into energy?
It is easy to see how our traditional diets are low quality by comparing them to the diets of a handful of primates that live almost entirely off of insects, or tree sap, or nectar. If we look at birds, we see the same thing; many species of birds eat pure sugar of one form or another. A few other animals have very high quality diets. Generally, carnivores have higher quality diets than herbivores. There are no carnivores that use multiple stomachs or habitually regurgitates and re-consume their animal prey in order to digest it. Herbivores that eat grass or leaves spend a lot of time feeding, have massive digestive systems designed by natural selection to digest the hell out of the food, and sometimes they have to “eat” the same food multiple times to get enough energy out of it to survive. Humans are somewhere in between. Some of our digestion is done pre-consumption by cooking and processing, but for the most part our natural, traditional diet takes a fair amount of work to process. We don’t live off of sugar water like hummingbirds and many insects do.
And this is why the leading cause of death in the United States and some other countries has shifted from the usual panoply of causes – infectious disease, accident, homicide, etc. – to our diets. Our diet is the most likely thing to kill us, and lately, the primary mediating factor in this particular cause of death is obesity and/or diabetes.
The “traditional” diet of any group of people, as I’ve already outlined, is relatively recent historically, being the result of 10,000 years of developing plants and a few hundred years of transferring crops and growing methods across the world. That traditional diet was prominent globally through the 19th century and well into the 20th century. The food came from farms, and although many amazing novel technologies were being applied on those farms, such as better plows and various other things that could be drawn behind oxen, a team of ponies or horses, or a small tractor, those technologies did not change the diets too much.
But as technologies developed, farms began to scale up. This is the reason that the New England countryside is graced with young forests criss-crossed with quaint stone walls. Those stone walls were field boundaries in the old days. But as farming scaled up, it became economically inviable to have small fields on small farms. A few other things went wrong on some of these New England farms as well, including some climate glitches and some other economic effects that drove farmers off the land and in some cases into cities where there were jobs working in mills. But some of those farmers took part in the great Westward Migrations, as the country grew, and established a new kind of agriculture in the vast regions of the midwest and plaines.
Add a growing urban market for foods, government help in the form of extension and agricultural colleges, more technology such as combines, railroads to move produce to market, mills to process the produce, add some water (irrigation) as needed and salt to taste. It took decades, but we went from an agrarian economy where the same traditional diet we had been eating was produced on a somewhat larger scale, to an agricultural economy that produces mostly one single thing. This product:
OK, I’m exaggerating there. It isn’t really true that the entire US agricultural system has been converted over to the production of sugary drinks. But sometimes it seems that way. Vast expanses of corn are grown in the midwest and plains, and that corn is used to produce vast amounts of ethanol (as fuel), alcoholic beverages, sugary substances including cola, feed for animals, and some of it even makes it to the table as … well, corn. But lets step back to the original comparison of “traditional diet” and the diet many Americans eat today.
When you eat a traditional meal, a good amount of that food is low quality, relatively hard to digest, carbohydrates with a mix of proteins. There will be a little simple sugar here and there and a bit of fat here and there.
The simple sugars go right away to the liver, where they supplement the body’s immediate energy stores. The complex sugars, the carbohydrates that consist of much larger and more involved molecules, take time to digest and break down to eventually use as fuel. So the sugar gives you a small amount of immediate energy and the complex carbohydrates give you energy over the coming hours.
The fats are simply stored up. If you eat fat, the fat molecules are minimally processed, moved to your hips or wherever, and are pasted there for later use. Or, forever, depending.
When you eat a modern diet, it will have two major difference from the traditional diet. The foods at the two ends of that spectrum of availability will be in greater proportion. Instead of having a bunch of low quality food in the middle, with a little fat (for later) on one end of the spectrum, and a little simple sugar (for immediate use) on the other end of the spectrum, the modern diet will have piles of fat and piles of simple sugar and not much in between.
So, what happens? The fat goes where fat goes, as stated already, but there is more of it. The sugar overloads the liver, which detecting an overabundance of energy, converts the sugar to some form of storage, and some of that is fat that joins up with the other fat. There is also a kind of molecule the liver converts some of that sugar into, stored in your liver, for in case you get hungry between meals. That molecule reduces the chance your body will use any of that stored up fat as energy.
Two thousand traditional calories provides you with energy for now, energy for the next several hours, and a bit of energy for much later. Two thousand modern calories provides you with way more energy than you need for now, and a huge amount of fat that you’ll never use because you are never going to let much time go between meals. Because there is a fast food joint just down the street. And your refrigerator and cabinets are full of junk food.
And that’s not all. Our system of agriculture has all sorts of other negatives as well. The following is from the Food and Agriculture page of the Union of Concerned Scientists:
Food and Agriculture: Toward Healthy Food and Farms
Our agricultural system has lost its way.
Millions of acres of corn, soybeans, and other commodity crops, grown with the help of heavy government subsidies, dominate our rural landscapes.
To grow these crops, industrial farms use massive amounts of synthetic fertilizers, herbicides and pesticides, which deplete our soil and pollute our air and water.
Much of this harvest will end up as biofuels and other industrial products—and most of the rest will be used in CAFOs (confined animal feeding operations) or in heavily processed junk foods, which seem cheap only because their hidden costs don’t show up at the cash register.
Industrial agriculture is unhealthy — for our environment, our climate, our bodies, and our rural economies.
A Better Way: Sustainable Agriculture
There’s a better way to grow our food. Working with nature instead of against it, sustainable agriculture uses 21st-century techniques and technologies to implement time-tested ideas such as crop rotation, integrated plant/animal systems, and organic soil amendments.
Sustainable agriculture is less damaging to the environment than industrial agriculture, and produces a richer, more diverse mix of foods. It’s productive enough to feed the world, and efficient enough to succeed in the marketplace—but current U.S. agricultural policy stacks the deck in favor of industrial food production.
Yesterday, I went to a symposium hosted at the Humphrey Institute at the University of Minnesota and organized by the Center for Science and Democracy at the Union of Concerned Scientists. A description of the symposium is here and the entire thing was “taped” and will be available. I’m not going to tell you anything major about the symposium now; I’ll wait until the video is available, then I’ll provide you with my thoughts on it. For now I’ll just say it was quite good, eye-opening, and that you’ll definitely want to watch it. In fact, you should feel a little bad that you weren’t there.
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…
I had mentioned earlier that the volcanoes of the Virugna region in the Western Rift Valley (as well as other highland spots) have often been islands of rain forest separated from each other by different habitats, including grasslands and wooded savannas. this has produced an island effect that has been a laboratory for evolution, and it is likely that these forest islands (and others in the greater region of east Central Africa and western East Africa) have been the loci of evolution of many endemic species. (See Island Africa: The Evolution of Africa’s Rare Animals and Plants by Kingdon for an excellent overview of the Island Effect in highland regions of Central and East Africa.)
It is probably not a coincidence that two of the three subspecies of gorilla live within sight of each other (and of the main subspecies, the lowland gorilla) within this region. The Virunga volcanoes are not old enough to have supported island forests for the evolution of these specific subspecies, but other highlands in the region, or other volcanoes (perhaps in the Eastern Rift) may well have been the location in which they evolved.
And, as it turns out, there is reason to believe that the split between chimps and humans occurred on one of these volcanic mountain tops several million years ago. Or, at least, in an environment geologically similar to the upper reaches of the Virunga Volcanoes. But to tell this story right, I have to go back a few years. Continue reading Nyamulagira Volcano and Human Evolution→
… and made a real mess of the place when one of them spotted the jar of pickles on the counter. They fought over it until one of them had almost all the pickles and the other one had a number of bruises and a tiny fragment of one pickle that the other chimp dropped by accident.
That would be the way it would happen if two chimps walked into a bar. Or imagine two chimps, and each finds a nice juicy bit of fruit out in the forest. And instead of eating the fruit, because they are not hungry, they carry it around for a while (this would never happen, but pretend) and then accidentally run into each other. What would happen? Same thing. Event though neither chimp actually needed the fruit and each chimp had its own fruit, the dominant chimp (between the two) would end up with both pieces of fruit.
This is why chimps could not possibly cooperate in any effort to scour the forest for various edible items, bring them all back to a central place, share and then cooperatively process the food items, and ultimately produce a meal that is eaten by all of the chimps on an as needed basis. Humans do that but chimps can’t. Explain this and you explain one of the major features of human evolution… Continue reading Two chimps walked into a bar …→
Much is made of the early use of stone tools by human ancestors. Darwin saw the freeing of the hands ad co-evolving with the use of the hands to make and use tools which co-evolved with the big brain. And that would make the initial appearance of stone tools in the archaeological record a great and momentous thing. However, things did not work out that way. Continue reading Great Moments in Human Evolution: The Invention of Chipped Stone Tools→
One of the most interesting and exciting stories in science is that of the Younger Dryas. The Younger Dryas was a climate event that had important effects on human history, and that has been reasonably linked to some of our most important cultural changes, and ultimately some evolutionary changes as well. That is one reason why it is interesting. In addition, the Younger Dryas was a pretty big deal … a climate change or something like a climate change that caused massive changes all around the earth, and fairly recently. But the cause of the Younger Dryas is at present unknown, although a series of explanations have been advanced, each as convincing as the next depending on one’s point of view. The Younger Dryas itself is interesting, and the story of how scientists have studied it and the changing explanations emerging from that research is just as interesting.
The latest science is beginning to suggest that it is all even more interesting and exciting (and scary) than previously thought.
Fallback foods are the foods that an organism eats when it can’t find the good stuff. It has been suggested that adaptive changes in fallback food strategies can leave a more distinct mark on the morphology of an organism, including in the fossil record, than changes in preferred food strategies. This assertion is based on work done by the Grants and others with Galapagos Island finches, by Richard Wrangham and me with hominids, and by Betsy Burr and me with rodents. Continue reading The Potato and Human Evolution→
From Scientific American, a piece on the “Cooking Hypothesis” (which yours truly helped develop some years back).
Our hominid ancestors could never have eaten enough raw food to support our large, calorie-hungry brains, Richard Wrangham claims. The secret to our evolution, he says, is cooking
Cooking does indeed turn a lot of stuff that is not edible to humans (or any primate) into usable energy. We think the increase in body size that comes along with the genus Homo (with Homo erectus and kin) is itself a biological signal of cooking.
The problem with his idea: proof is slim that any human could control fire that far back. Other researchers believe cooking did not occur until perhaps only 500,000 years ago. Consistent signs of cooking came even later, when Neandertals were coping with an ice age. “They developed earth oven cookery,” says C. Loring Brace, an anthropologist at the University of Michigan at Ann Arbor. “And that only goes back a couple hundred thousand years.” He and others postulate that the introduction of energy-rich, softer animal products, not cooking, was what led to H. erectus’s bigger brain and smaller teeth.