During evolution, living species have adapted to environmental constraints according to the mechanism of natural selection; when a mutation that aids the survival (and reproduction) of an individual appears in the genome, it then spreads throughout the rest of the species until, after several hundreds or even thousands of generations, it is carried by all individuals. But does this selection, which occurs on a specific gene in the genome of a species, also occur on the same gene in neighboring species? On which set of genes has natural selection acted specifically in each species?
Researchers in the Dynamique et Organisation des Génomes team at the Institut de Biologie of the Ecole Normale Supérieure (CNRS/ENS/INSERM) have studied the genome of humans and three other primate species (chimpanzee, orangutan and macaque) using bioinformatics tools. Their work consisted in comparing the entire genomes of each species in order to identify the genes having undergone selection during the past 200,000 years. The result was that a few hundred genes have recently undergone selection in each of these species. These include around 100 genes detected in man that are shared by two or three other species, which is twice as many as might be anticipated as a random phenomenon. Thus a not inconsiderable proportion of the genes involved in human adaptation are also present in the chimpanzee, orangutan or macaque, and sometimes in several species at the same time. Natural selection acts not only by distancing different species from each other when new traits appear. But by acting on the same gene, it can also give rise to the same trait in species that have already diverged, but still have a relatively similar genome.
This study thus provides a clearer understanding of the group of genes that are specifically implicated in human evolution (during the past 200,000 years), as it allows the identification of those genes which did not undergo selection in another primate line. An example that has been confirmed by this study is the well-known case of the lactase gene that can metabolize lactose during adulthood (a clear advantage with the development of agriculture and animal husbandry). The researchers have also identified a group of genes involved in some neurological functions and in the development of muscles and skeleton.
You may have more in common with Kanzi, Panbanisha and Nyota, three language-competent bonobos living at Great Ape Trust, than you thought. And those similarities, right at your fingertip, might one day tell scientists more about the effect of culture on neurological disorders that limit human expression. Among humans, pointing is a universal language, an alternative to spoken words to convey a message. Before they speak, infants point, a gesture scientists agree is closely associated with word learning. But when an ape points, scientists break rank on the question of whether pointing is a uniquely human behavior. Some of the world's leading voices in modern primatology have argued that although apes may gesture in a way that resembles human pointing, the genetic and cognitive differences between apes and humans are so great that the apes' signals have no specific intent. Not so, say Great Ape Trust scientists, who argued in a recently published scientific paper, "Why Apes Point: Pointing Gestures in Spontaneous Conversation of Language-Competent Pan/Homo Bonobos," that not only do Kanzi, Panbanisha and Nyota point with their index fingers in conversation as a human being might, these bonobos do so with specific intent and objectives in mind.
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