University of California Press. Human Biology 86 3 : American Anthropologist 2 : Gamble, C. Cambridge Archeological Journal 21 1 : Gowlett, J. Thames and Hudson. Hodder, I. Ingold, T. Cambridge University Press. Jablonka, E.
MIT Press. Kendal, J. Biological Theory 6 3 : Philosophical Transactions of the Royal Society B : Kuzawa, C. Laland, K. Journal of Evolutionary Psychology 5 : Nature Reviews Genetics 11 2 : Nature : Proceedings of the Royal Society B Marks, J. Paper Current Anthropology 53 4 : Odling-Smee, J.
Monographs in Population Biology Princeton University Press. Paenke, I. The American Naturalist 2 : EE Raff, J. Stein, L. Tattersall, I.
Palgrave MacMillan. New York. Wade, N. Penguin Press. Wake, D. Proceedings of the National Academy of Sciences S2 : Wells, J. Universidad de Notre Dame , Estados Unidos. A basic, early twenty-first-century understanding of how evolution works is captured in the following five statements: 1. References Aiello, L. The interaction between organisms and evolutionary forces; [e. Meyer and his colleagues hope to improve their methods enough to obtain some or all of the Sima de los Huesos individual's nuclear genome, the DNA from the nuclei of its cells.
It is now a matter of when, not if, someone will produce a genome from an Arctic animal buried in permafrost for longer than 1 million years, says Meyer. And Orlando says that researchers may have luck using new extraction techniques on previously vexing remains such as Egyptian mummies or Homo floresiensis , a small hominin at least 18, years old that was found in a cave on the Indonesian island of Flores. A few years ago, David Reich discovered a ghost. Reich, a population geneticist at Harvard Medical School in Boston, Massachusetts, and his team were reconstructing the history of Europe using genomes from modern people, when they found a connection between northern Europeans and Native Americans.
They proposed that a now-extinct population in northern Eurasia had interbred with both the ancestors of Europeans and a Siberian group that later migrated to the Americas 6.
Reich calls such groups ghost populations, because they are identified by the echoes that they leave in genomes — not by bones or ancient DNA. Ghost populations are the product of statistical models, and as such should be handled with care when genetic data from fossils are lacking, says Carlos Bustamante, a population geneticist at Stanford University in California.
Evolution is everywhere
Sometimes these statistical spectres get a body. Last year, Willerslev's team reported 5 the genome from 24,year-old remains dubbed the Mal'ta boy. Ghost populations also lurk in ancient DNA. While analysing high-quality genomes of a Neanderthal and a Denisovan, a team led by Reich and Montgomery Slatkin at the University of California, Berkeley, noticed a peculiar pattern: present-day sub-Saharan Africans are more closely related to Neanderthals than they are to Denisovans 4.
But evidence from other ancient genomes suggested that the two archaic groups were equally related to present-day Africans.
After weighing the possibilities, the scientists realized that they might have uncovered another ghost population. The puzzle could be solved, they theorized, if Denisovans had interbred with a species that had left Africa perhaps more than 1 million years ago and branched off from the common ancestor of humans, Neanderthals and Denisovans. Subsequent Denisovans would have inherited DNA sequences that present-day Africans lack, explaining why Neanderthals seem to be closer kin to Africans. Reich's team is analysing genetic signatures in humans with Denisovan DNA to establish when the Denisovans mated with this mystery population — information that could narrow the range of fossils to which it might belong.
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Reich is not the only one conjuring ghosts. Chris Stringer, a palaeoanthropologist at the Natural History Museum in London, has proposed that the ,year-old hominin Homo antecessor , known from fossils found near Sima de los Huesos, could be part of the ghost population. If it had interbred with an ancestor of the Denisovans and the Sima de los Huesos hominins, it could explain the relationship between the two groups of remains.
If early human populations bred with Neanderthals and Denisovans, their descendants should carry short segments of archaic-human DNA. Researchers such as Akey are beginning to catalogue these segments to learn about the biology of archaic humans. Unlike the hunt for ghost populations, which relies on statistical population models, this approach allows researchers to identify specific regions of the genome acquired by interbreeding.
But giant swathes of the modern genomes were devoid of Neanderthal ancestry, hinting that many Neanderthal genes might have been harmful in modern humans. Akey's team identified 7 one such region around the gene FOXP2 , which is involved in speech and language. These discoveries are only the beginning. Akey sees this as possible evidence that Neanderthals interbred with ancient humans on at least two separate occasions: once with the ancestors of all Eurasians, and later with a population ancestral only to east Asians.
And Akey believes that humans are likely to bear genetic scraps from other extinct species, including some that interbred with the ancestors of humans in sub-Saharan Africa.source url
For much of the past 30 years, the sensitivity of the polymerase chain reaction PCR , the method used to amplify ancient DNA, made it prone to contamination. The field's leaders often greeted the work of outsiders with suspicion, earning some of them the title 'the PCR police'. That is set to change. New procedures mean that researchers can now reliably obtain DNA from all but the most degraded samples, and then sequence only the portions of a genome that they are interested in.
Gradually, new researchers are entering the field. His research originally focused on ancestry in current human populations. Then, a few years ago, he got a phone call about a mummy. Professor Berger said Homo erectus was the earliest human ancestor, but it was unclear which species it had descended from. It may have been Homo habilis or Homo rudolfensis.
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But Au. He said apes had long fingers and short thumbs but their hands were a lot like humans'. The hand was amazing to see, ''particularly on the end of an arm that's like an ape,'' Professor Berger said.