Part III: What Evolution Does in VS .NET

Painting QR Code ISO/IEC18004 in VS .NET Part III: What Evolution Does

lthough many of us like to tell ourselves that we re different from other organisms in some fundamental ways, we re all subject to evolutionary processes So evolution doesn t pertain only to animals, plants, bacteria, etc It pertains to humans as well As this part explains, we have our own evolutionary history as a species and an evolutionary future, as well Ironically, the other species that poses the biggest challenge and threat to us and therefore deserves attention in this part is the one we can t even see (without help): the microbes, like bacteria and viruses, organisms that evolve amazingly quickly and in response to the medicines we use to fight them

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Sorting through the bones of our ancestors Migrating out of Africa Searching for the key events of human evolution

ost people are very interested in human evolution and know something about it but still find the topic perplexing They have an inkling, for example, that humans evolved from apes (actually, apelike creatures) but think that evolution works differently for humans than it does for other organisms It doesn t The same evolutionary principles that apply to every living organism apply to human beings: speciation, genetic drift, coalescence, you name it This chapter explains both the evolutionary origin of our species and subsequent evolution within the species Homo sapiens In a way, this chapter answers two questions: Where did we come from and Where are we going

When you think about human evolution, you may think immediately about the fossil record Although fossils are extremely important parts of the evidence we humans have for understanding our own origins, other vital lines of evidence exist as well: Phylogenetic reconstructions: A phylogenetic reconstruction is essentially a visual representation of the genealogy of a group of species (refer to 9 for more details) This image can provide insight into where humans fit in the tree of life

Human DNA studies: By looking at our DNA, researchers can get intriguing information about the patterns of migration of Homo sapiens (humans) that help them sort out different hypotheses about where humans originated They can t get this info just by looking at fossils, which aren t always clear Neanderthal DNA studies: It s possible now to obtain DNA from one of our closest relatives: the Neanderthals By comparing modern human DNA with Neanderthal DNA, scientists gain a better understanding of our relationship to this extinct species of hominid

As I explain in 9, phylogenetics takes data about existing species and reconstructs the evolutionary branching pattern that led to those species Not surprisingly, no small amount of effort has been devoted to reconstructing the parts of the tree of life where humans reside Our particular branch includes the apes: gibbons, orangutans, gorillas, the two types of chimpanzees (the standard one that you re familiar with and the bonobo, which used to be called the pygmy chimp but which turns out to be a species of its own), and us! When biologists started wondering where all these creatures should reside on our branch of the tree, they imagined one sub-branch leading to us and another sub-branch leading to all those charming, furry creatures who seem so different from us Researchers could tell that, of all the animals, humans are most like apes, but in the past, they tended to think of the apes as belonging on the other twig of our shared branch of the tree Enter the amazing resource of DNA Now that scientists have been able to sequence human DNA as well as good samples of DNA from the other apes (in the case of the chimpanzees, the entire genome), they ve discovered that humans and chimps aren t very distant at all The current best hypothesis about the relationships between humans and the rest of the great apes is shown in Figure 16-1 In Figure 16-1, you can see that the two chimpanzee species (chimps and bonobos) have a most recent common ancestor These species are a lot more like each other than they are like anything else But surprise! humans have a most common ancestor with the chimpanzee lineage that we don t share with the other great apes To find the most common ancestor of gorillas, humans, and chimpanzees, you have to go back a bit farther and farther yet to find the most recent common ancestor of orangutans, gorillas, humans, and chimpanzees