Tag Archives: primates

Nyamulagira Volcano and Human Evolution

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

Ida the Fossil Primate

You probably know that there is a new primate fossil, nicknamed “Ida,” and that there is quite a buzz about it.

i-b3e6f4e69e21de46321c3e9416086c71-ida_head.jpg

Darwinius masillae, aka Ida

ResearchBlogging.org
Ida comes from fossil deposits in Germany, and was originally excavated in two different parts by private collectors, and only recently rejoined and recognized for the amazing fossil it is. This is considered to be a new genus, and is named Darwinius masillae

i-f722ecc23187c18e669eb47c946f03d9-IdaFossil.jpg

…holotype skeleton in right lateral view…

Ida is a 47 million year old adapid primate of outstanding, unprecedented state of preservation that seems to have some very interesting and possibly unexpected features that could shed light on the evolutionary relationships among the extinct primates. But before we get to that, we need to cover some background on primates, extinct and otherwise.

The first thing you need to know is that order of living primates can be divided into two groups: the suborders Strepsirrhini and the Haplorrhini.

Strepsirrhini includes the lemurs of Madagascar, and the lorises, pottos and galagos of Africa and Asia. In other words, Strepsirrhini are the Prosimians, more or less.

The Haplorrhini include the old world monkeys and the new world monkeys, and the apes, as well as this one strange group called the Tarsiers (which used to be in the Prosimians, which has caused some confusion.) The Haplorrhini are the “Anthropoid primates,” more or less.

Based on morphology and DNA and so on, it is believed that these two groups diverged from one another perhaps as far back as 80 million years ago (Murphy et al 2009). Subsequent to that time, the different smaller groups of primates (old world vs. new world monkeys, for instance) diversified.

i-ce05f70b61bfe5c32a47386f15074604-ida_onbranch_200.jpg

Artist reconstruction

Now, here is a basic problem that plagues primate evolutionary research. If you look at all the features that make a primate a primate (as opposed, say, to a tree shrew or some other mammal) using only living species, you get a workable set of features. If you take standard lemurs and, say, Old World Monkeys and you make a set of distinctions between those two groups, you get a reasonable set of criteria to distinguish among them. But, when you either add in Tarsiers (or some other primate groups) or start looking at fossils that are tens of millions of years old, it starts to get tricky. It becomes difficult to distinguish between convergence and common ancestry for certain traits. In other words, it is hard to tell if two traits are the same in two groups because the common ancestor of those groups had the trait and the specimens you are looking at both inherited this, or if the two lineages independently evolved the same trait.

“How likely is that to happen?” you may be asking yourself. Answer: Under some conditions, very very unlikely. Under other conditions, very likely. Let me explain.

Imagine we wanted to do a phylogeny of sedans. Once a line of car develops a square-back or pickup design, we eliminate it from our analysis. Sedans only. At the same time, some other research team is analyzing “powered vehicles” …. things that go with engines. This would include cars, trucks, boats, trains, and space ships. Even though both lineages may have been around for about the same amount of time, the sedan lineage would be much more prone to convergence because all sedans are almost exactly the same length, width, and height, have almost exactly the same number of seats, the same method for driving (like, auto vs. one stick) and so on, compared to the vehicles in the second study. The comparisons across vehicles that can carry nine tons of gravel, vehicles that can go under water, and vehicles that can fly are going to result in only the most trivial and easily exposed convergences.

i-cdee0f33c28ce8b5e617c5e8c6376025-IdaXray.jpg

Radiograph

Same with primates. At many important levels, all primates are the same. Compared to carnivores, all primates have almost the same pattern of teeth … there are very few variants on tooth pattern among all the primates that exist today, but many many variants for the carnivores. Even body size is fairly restricted for primates. Yes, there are a few whopping big ones, but compared to the elephants or the hyracoidea, not so much. With only a few exceptions, primates live in moist to wet heavily vegetated environments. Compare this to antelope, who have water-dependent and water-independent species. And so on.

Perhaps because of this limited range of variation, or perhaps causing this limiting range, is the simple fact that morpholgically all primates are primitive. So there is not some group of primates where the radius and ulna are fused, and a different group where they are not. All primates have unfused radius and ulna. There are not primates with vs. without some kind of grasping hand (I simplify slightly here). All primates have the same number of fingers and toes. In comparison, for instance, carnivores have varying numbers of toes and different patterns of bone fusions among them.

So that is the background. If you are going to look at ancient fossils, you’ve got a very conservative set of lineages so a) you’ll always recognize a primate, quite easily, when you see one and b) convergence will haunt you for your entire life if you are a paleo-primatologist.

For various reasons, especially the item noted above about the moist heavily vegetated habitats, but also the sparseness on the landscape and lightly built skeletons, primates make lousy fossils. There are very few places in the world where we have primate fossils, and they are much restricted in geographical space and time range. In short, the primate fossil record sucks. The primate fossil record is mostly teeth, and the teeth look all the same. All the work I’ve done in the primate fossil record has been in the Miocene, and that is not so bad. There are better conditions: You get some real fossils, even postcranial (body) bones, sometimes. But the pre-Miocene record is really scary.

Paleontologically, primates are anatomically ambiguous ghosts.

<

p class=”center”>i-0610d373c0da495a297c8a5234f378b8-Ida_teeth.jpg

As a juvenile, Ida has both deciduous (“baby”) teeth and adult teeth. More teeth = more data.

Within the fossil record, there are probably four or five sets of fossils that represent groups different from living primates, but most “crown” fossils can be placed into two major groups: The adapids and the omomyids. If either of these two groups could be linked to later, living primates, this would have to be done using a number of physical characteristics of the bone … there is not much chance of finding ancient DNA in these very old fossils.

This part of the fossil primate record includes the Adapoidea, including the widespread Adapids and some other fossil groups, but no living forms, and the Tarsioidea, which includes the fossil Omomyids, some other fossil forms, and the living Tarsius. The Adapids and Omomyids date mainly to the Eocene about 55 to 34 million years ago. Note that this is well after the Haplorrhini-Strepsirrhini split. Over the years, various groups of primatologists have attempted to link either of these groups to the major living groups of primates.

One subgroup of the Adapoidea is the Cercamoniinae, identified in the 1970s by one of the present paper’s authors, Philip Gingerich. This group exhibits a few traits that seem to link it with the living Haplorrhini (monkeys and apes). For example modern monkeys often have a premolar that is shaped a certain way to “hone” the canine. This is a bit unusual, and is a marker for this kind of modern primate. Something that looks like such a tooth appears, more or less, among the Cercamoniinae. This sort of connection (and other factors) has led some (Gingerich included) to link the Adapoidea in general to the modern anthropoid primates (monkeys and apes). Others disagree.

The fossil being reported now, Ida, is grouped by the authors into the Cercamoniinae. If that phylogenetic conclusion ends up being verified by further study, this excellent, well preserved fossil will be an important touchstone in interpreting early anthropoid (non-lemur) primate evolution and behavioral ecology.

The phylogenetic argument that is being made in this paper is admittedly preliminary (more work is promised on this) but so far it is very tricky and is likely to remain tricky. The structure of the prior arguments that links either of the two main fossil groups to either of the two main living groups has always been tenuous. The reason for this, as I’ve alluded to above, is that those two fossil groups fall about half way in time between the present and the original split of these groups, and there are not enough fossils between 80 and 55 million years ago to understand the details of that early split. Then, there are not enough fossils from about 34 million years ago to recent times to understand this later period during which the modern forms arose. While more work will be done on the phylogenetic relationships, considering that the contemporary fossils …. the old fossils roughly of the same age as “Ida” … are mostly teeth, and tens of millions of years separates Ida from the modern forms, I do not expect much more in the way of a resolution until more fossils like Ida, but of different species, are found.

Getting away from phylogeny, let’s have a look at other aspects of this fossil. This is a remarkably well preserved specimen. The animal probably died from volcanic gas (like C02) and fell into the water, and was slowly buried in fine sediment. Once encapsulated, the body began to rot, and the slime layer that started out as the animals’ flesh, skin, and fur approximated the outer surface of the body and was preserved in the fine sediment as well. The sediments in which this fossil is preserved are compressed, so the entire skeleton is uniformly crushed, slightly, but everywhere, affecting every bone. In order to visualize and measure the specimen, fancy 3D imaging and image processing techniques were applied.

The animal was a juvenile female and weighted between 385 and 580 grams, and would have grown up to be about 660 grams by one estimate, or a whopping 1600 or 1700 grams by another estimate. Since the larger estimate is based on molar size, which in turn can be secondarily influenced by adaptations to diet, I’d go with the lower estimate. Indeed, using the brute force method of holding the fossil up to full scale pictures of living primates to find one that matches, the estimated adult body size is about 845 to 892 grams.

The contents of the digestive track were preserved (that is extraordinary) and include leaves and fruit. There are no insect remains in the gut.

You are going to hear more about this fossil, as more analysis is done. I have two meta-remarks to make about this finding. First, there was a lot of hype about how this fossil is a “missing link” and so on and so forth. That was overdone. But equally overdone is the reaction to the hype. Almost every blog post or other secondary report I’ve seen on this has talked almost as much … or more … about the hype than about the fossil. Second, please note that this find was reported in PLoS ONE, an open access on line journal. This means that you can see the report yourself, look at all the cool pictures, and try if you must to slog through the highly technical text. This is big for Open Access publishing.

<

p class=”center”>i-c3df4c30086f547cc038a35ba85f1d0c-side_drawing.jpg

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Franzen, J., Gingerich, P., Habersetzer, J., Hurum, J., von Koenigswald, W., & Smith, B. (2009). Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology PLoS ONE, 4 (5) DOI: 10.1371/journal.pone.0005723

Murphy, W., Pringle, T., Crider, T., Springer, M., & Miller, W. (2007). Using genomic data to unravel the root of the placental mammal phylogeny Genome Research, 17 (4), 413-421 DOI: 10.1101/gr.5918807

There is a LOT of blogospheric and media coverage on this find. I was going to provide a list of links and then realized that there is only one good way to do this … I’m sending you here, to A Blog Around the Clock. Bora has every single link.

All of the images used above come from the original on line article.

Chimps in captivity are a problem.

The incident just reported an hour or so ago is unusual, but not unexpected or unheard of.

A 200-pound chimpanzee kept as a pet and once used in commercials was shot and killed by police Monday after it mauled a woman visiting its owner and later cornered an officer in his cruiser, authorities said.

Stamford police Lt. Richard Conklin said the injured woman was hospitalized late Monday in “very serious” condition at Stamford Hospital; her identity was not immediately released. Conklin said she suffered “a tremendous loss of blood” from serious facial injuries.

source

Great Moments in Human Evolution: The Invention of Chipped Stone Tools

Or not.

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

How diverse were early hominoids?

And hominids.

We know the fossil record underestimates diversity at least a little, and we know that forested environments in Africa tend to be underrepresented. Given this, the diversity of Miocene apes may have been rather impressive, because there is a fairly high diversity in what we can assume is a biased record.

But I’d like to make the argument from another angle, that of modern ecological analogues. Let us assume that the greater apparent diversity of apes in the middle and late Miocene compared today can be accurately translated as a modern reduction in ape diversity. Not counting the relatively diverse lesser apes, there are five species (2 chimps, gorilla, human, orang) which can be further divided into 10 subspecies, across the entire old world.

Now look at the size range of all of the living apes. Gibbons are the smallest and gorillas the largest. When a family or subfamily of land mammal is diverse in a particular region (a biome or something larger than a biome) we tend to see that diversity played out along a spectrum of size, and against size we can find additional diversity derived from dietary or subhabitat differences and geography. It seems to me that there is room in the size spectrum between gibbons and chimps, and orangs and gorillas, and there is certainly room above the gorilla size as indicated by the existence in the fossil record of very large Asian forms.

We know that some of the later Miocene apes were bipedal, and it is starting to look like bipedalism or something like bipedalism is showing up among other apes in the Miocene as well. So perhaps there is a spectrum of locomotory pattern along which diversity may be spread.

This gives us a the following size classes: gibbon, siamang, [something in between], chimp, orang, [something in between], goriilla, [something bigger], or at total (a minimum?) of eight size classes across which apes might exist in a world in which apes are divers. Like the Miocene. If we add to this a more arboral form and a more bipedal form, perhaps we double the number, or perhaps we add about five new classes (I’m guessing that a Mighty Joe Young size ape would not have been bipedal!). This gives us about a dozen, conservatively estimated, niches when we divvy up size and so-called positional behavior.

To this we can add geography. It is probably reasonable to assume that a wetter, more forested middle and late Miocene Africa could be divided into at least four or regions, between the West/Central divide that modern biogeogrpahy tells us was effective at least in the Late Miocene, the Congo River divide, North/Central Africa, East Africa and Southern Africa. Let’s conservatively assume four, and let’s assume that only half (six) of the hypothesized ape species are divided among these areas. That means that 24 species are endemic to varoius regions, and six additional species are more widely spread for a conservative estimate of 30 species.

Among these species there may have been several bipedal forms, but only one of them (plus or minus a little hybridization hanky panky here and there) would have been the human ancestor. Of course, no one at the time suspected that …. (Or they probably would have done something about it.)

This is not an outrageous suggestion. The idea that if you went back in time to a more ape-rich time (and we know it was more ape-rich) and got a current copy of the Guide to the Mammals of Africa, the ape section would have a few dozen species, just like the monkey section or the antelope section today has a few dozen species.

Go apes!

New Primate Research

I have had a lot of students of whom I’m very proud because of their accomplishments both in research and generally. One of these students is Mark Foster, who is one of a very small number of undergraduates to engage in significant research at some of the key East African chimpanzee research sites. Unfortunately for me, I can’t take a lot of credit for Mark’s excellent research, because I played a much smaller role in working with him than did others, but I am still very happy with his successes.

I’ve got a peer reviewed paper by Mark that I’ll be reviewing soon. In the mean time, have a look at this piece from Nature News

Researchers at the University of Minnesota’s Jane Goodall Institute Center for Primate Studies have now collated ten years of behavioural data on three male chimpanzee in Gombe National Park, Tanzania. Chimpanzees within the park have been routinely weighed by park staff, allowing Mark Foster and his team from the institute to work out which tactics chimpanzees of dramatically different sizes used both before and after they became alpha males….

The findings … are the first to suggest that physically smaller males make up for their reduced physical characteristics by using grooming to make allies who will aid them when their time comes to try and achieve alpha-male status, says Foster….

“It’s kind of like when I was a teenager and the football team’s quarterback lost the school’s popularity poll to a wimpy, unassuming fellow who was also quick-witted. The latter fellow was able to make friends through his sense of humour and charisma, and in turn achieved a kind of alpha status over the brutish quarterback,” he says.

You can probably access the story here.

Lemur Scent and Kin

i-547abcbd970038bf90ca66a87feca9df-ringtail.jpg

Perhaps judging a man by his cologne isn’t as superficial as it seems.Duke University researchers, using sophisticated machinery to analyze hundreds of chemical components in a ringtailed lemur’s distinctive scent, have found that individual males are not only advertising their fitness for fatherhood, but also a bit about their family tree as well.”We now know that there’s information about genetic quality and relatedness in scent,” said Christine Drea, a Duke associate professor of biological anthropology and biology. The male’s scent can reflect his mixture of genes, and to which animals he’s most closely related. “It’s an honest indicator of individual quality that both sexes can recognize,” she said.Lemurs, distant primate cousins of ours who split from the family tree before the monkeys and apes parted ways, have a complex and elaborate scent language that until recently was completely undiscovered by humans. Drea said it’s language that is undoubtedly richer than we can imagine.”All lemurs make use of scent,” she said. “The diversity of glands is just amazing.”Ringtailed males have scent glands on their genitals, shoulders and wrists, each of which makes different scents. Other lemur species also have glands on their heads, chests and hands. Add to these scents the signals that can be conveyed in feces and urine, and there’s a lot of silent, cryptic communication going on in lemur society.Wearing a scent-based nametag declaring one’s genetics is probably useful in avoiding aggression with closely related males, Drea said. It’s also quite likely to help prevent inbreeding by signaling family relationships to females, but the research to prove that is still ongoing.For this study, Drea and postdoctoral fellows Marie Charpentier and Marylène Boulet focused solely on male ringtailed lemurs living at the Duke Lemur Center.The males have a gland and spike on each wrist that is used to scratch and mark saplings with highly aromatic scents. A pair of glands on the shoulders “like misplaced nipples” manufacture squalene, a scent molecule that works like glue to keep the more aromatic compounds in place longer. Males can be seen dabbing the wrist gland on the chest gland and then scratch-marking. The wrist glands are also central to the “stink fighting” of ringtails, in which they rub the glands along the length of their bushy tails, and then foist them into each others’ face to express dominance.Most importantly, the male also has a scent gland on his scrotum that becomes critical to marking territory and advertising fitness during mating season. He does a handstand and rubs this gland directly onto a tree trunk to let any interested lemurs know who he is and what he’s made of.Scent not only speaks volumes, it’s physiologically expensive to make, Drea said. When a lemur is ill or socially stressed, its scent changes dramatically. “If he loses his signals, it’s quite likely its because he’s less genetically fit,” Drea said. “And his sexual or social partners can know that.”Female ringtailed lemurs have just one scent gland in the genital area, but their scent is more complex than the males’. Via scent, females may advertise not only their fertility, but the presence of a pregnancy and how far along it is, Drea said….source and more

Chimpanzee Food Sharing

Is chimpanzee food sharing an example of food for sex?

i-3691706735948748b5a89f0a306951ac-chimp_share_tree.jpgOne of the most important transitions in human evolution may have been the incorporation of regular food sharing into the day to day ecology of our species or our ancestors. Although this has been recognized as potentially significant for some time, it was probably the Africanist archaeologist Glynn Isaac who impressed on the academic community the importance of the origins of food sharing as a key evolutionary moment. At that time, food sharing among apes was thought to be very rare, outside of mother-infant dyads. Further research has shown that it is in fact rare … the vast majority of calories consumed by human foragers in certain societies and at certain times of the year comes from a sharing system, while the fast majority of calories consumed by chimpanzees is hand to mouth without sharing.

Continue reading Chimpanzee Food Sharing

Robot Does Monkey’s Bidding

i-4e0f7898e50a73fff978bc6fe8703d60-robot_monkey.jpg
Two hundred pound robot lumbering along on tread mill, doing the bidding of a monkey several thousand miles away.
An international and interdisciplinary team of scientists have developed a robot that will carry out physical activities in imitation of the activities of a monkey. The monkey and the robot are hooked together via the internet. The monkey has a brain-machine interface. When the monkey moves along on a treadmill, the robot mirrors those movements. The monkey and the robot need not be anywhere near each other, of course. In fact, it is probably a good idea to keep them in separate places. If the robot knew that its entire existence was really just to be an automaton doing the bidding of a monkey, if it realized that it was a mere simian-driven Golem, it may become depressed or go berserk. Continue reading Robot Does Monkey’s Bidding

Jane Goodall: What separates us from the apes?

Traveling from Ecuador to Africa, Jane Goodall takes the audience on an ecological journey, discussing highlights and low points of her experiences in the jungle. She shows how progress is helping research (DNA analysis) and hurting the environment (clear-cutting). And she draws a dozen parallels between primate and human behavior, making the point that we really aren’t all that different. Our big advantage, she says, is the ability to communicate with sophisticated spoken language — yet, sadly, we are abusing this power and destroying the planet. She urges the TED audience to behave differently, and use their higher powers to correct the planet’s course.

Continue reading Jane Goodall: What separates us from the apes?

Baby Orangutan

There is a new baby orangutan born at the Como Zoo in Saint Paul, Minnesota. I mention this for the edification of my local readers (who probably already know about it) and not as a statement of support or opposition to zoos, orangutans, or babies.Details, including photographs, here on Science Buzz.