Darwin hypotheses that in general, the extremes tend to be selected, as each finds a different means of surviving in changed environments, though its important to note that sometimes none or too few of the animals have the needed characteristics. In this case, the population or species goes extinct. As a result of some varieties being selected and some going extinct, "gaps" appear between populations over time. This is known as "divergence of character".
Explosive population growth is driving human evolution to speed up around the world, according to a new study.
The pace of change accelerated about 40,000 years ago and then picked up even more with the advent of agriculture about 10,000 years ago, the study says.
A team of scientists led by Yale University evolutionary biologist Stephen Stearns suggests that if the natural selection of fitter traits is no longer driven by survival, perhaps it owes to differences in women's fertility. "Variations in reproductive success still exist among humans, and therefore some traits related to fertility continue to be shaped by natural selection," Stearns says. That is, women who have more children are more likely to pass on certain traits to their progeny.
Right. The tremendous fossil discoveries of late have given us a lot more knowledge about the diversity of human experiments, and diversity is the theme that needs to be underlined. Yet in spite of the great variety in earlier human species, we are the only one that remains of a diverse family tree. That might seem to indicate something special about us, but in fact even we barely made it.
The pattern and process of human evolution can be described on the basis of a combination of comparative anatomy, fossil record, and primate and human genetics (Kimbel and Martin, 1993). Comparative anatomy, even in Darwin's time, indicated a close relationship between humans and African apes (Huxely, 1863), and this has been confirmed by comparative genetic analyses.
With mankind the differences between the sexes are greater than in most species of Quadrumana, but not so great as in some, for instance, the mandrill. Man on an average is considerably taller, heavier, and stronger than woman, with squarer shoulders and more plainly-pronounced muscles.
...this embryo has essentially the anatomical structure of a Lancelet, later of a Fish, and in subsequent stages those of Amphibian and Mammal forms; and that in the further evolution of these mammal forms those first appear which stand lowest in the series, namely, forms allied to the Beaked Animals (Onithorhynchus); then those allied to Pouched Animals (Marsupialia), which are followed by forms most resembling Apes; till at last the peculiar human form is produced as the final result.
Since scientists developed the ability to decode the genome and compare the genetic makeup of species, some people have been stunned to learn that about 98.5% of the genes in people and chimpanzees are identical. This finding means chimps are the closest living biological relatives to humans, but it does not mean that humans evolved from chimps. What it does indicate is that humans share a common ancestor with modern African apes (i.e., gorillas and chimpanzees), making us very, very distant cousins. We are therefore related to these other living primates, but we did not descend from them.
Professor Steve Jones, of University College London, says the forces driving evolution - such as natural selection and genetic mutation - no longer play an important role in our lives.
The people living one million years from now, should Man survive, will resemble modern-day humans.
Australopithecus is a genus of hominins now extinct. Ape-like in structure, yet walking bipedally similar to modern humans, they are believed to have played a significant role in human evolution, and it is generally held among anthropologists that a form of Australopithecus eventually evolved into Homo.