Category Archives: Mammals

A question about your squirrels

My friend Asha just gave a copy of Squirrel Wars: Backyard Wildlife Battles & How to Win Them to her mom for Father’s day. Which reminds me of this method of controlling squirrels in your back yard.

Which, in turn, reminds me that I’ve been meaning to ask around about color morphs. Where I grew up, gray squirrels were gray. I lived in Boston for many years, and gray squirrels there were … also gray. Well, the ones in Harvard Yard were more a shade of grey. Anyway, here in the Twin Cities area, they are pure white, almost jet black, or gray. Some of the gray ones are reddish gray.

So, here is my question: Am I living in a region where there is unusual diversity in the color morphs of Sciurus carolinensis? What is the diversity of gray squirrel pelt color in your region?

And why?

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

Global warming and the Minnesota Moose. Part I.

Minnesota moose experts generally agree that global warming is forcing the southern edge of the distribution of the moose northward into Canada, threatening this important US population of this ginormous deer species. Global warming denialists insist that this is the moose’s fault, and has nothing to do with global warming. This is the first of a two part look at this question.
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This is an Alaskan moose. But someday he hopes to visit its relatives in Minnesota. If they live long enough…

Continue reading Global warming and the Minnesota Moose. Part I.

Global Warming, The Decline of the Moose, and “Minnesota Nice”

We have had a cool summer here in Minnesota, and this has brought out the miscreants who for their own reasons do not want to get on board with the simple, well demonstrated scientific fact that global temperatures have risen, that we humans are the primary cause, and that this climate change has negative consequences.

Continue reading Global Warming, The Decline of the Moose, and “Minnesota Nice”

Evolutionary enamel loss linked to molecular decay of enamel-specific gene

The evolutionary history of mammals can be reviewed as the evolutionary history of tooth loss. The early mammals had many teeth, and every now and then in evolutionary time, a tooth is lost wiht subsequent species arriving from that n-1 toothed form having that smaller number of teeth. With ver few exceptions, no mammals have added a tooth during the history of mammals. (Excepting maybe the very very earliest period, but probably not.)

ResearchBlogging.orgWell, the loss of enamel itself is also an evolutionary trend in mammal history, and recent research published in PLoS Genetic associates genetic changes over time with what is known of the morphological evolution of mammals.

Continue reading Evolutionary enamel loss linked to molecular decay of enamel-specific gene

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.