Human evolutionPresentation #4

Juan Sebastian RodríguezCubillos

Biology L2 Project 9-A

Introduction:

• Is the evolutionary process leading up to the appearance of modern humans. While it began with the last common ancestor of all life, the topic usually covers only the evolutionary history of primates, in particular the genus Homo, and the emergence of Homo sapiens as a distinct species of hominids (or "great apes").

Genetic studies:

• Genetic studies show that primates diverged from other mammals about 85 million years ago in the Late Cretaceous period, and the earliest fossils appear in the Paleocene, around 55 million years ago. The family Hominidae diverged from the Hylobatidae (Gibbon) family 15-20 million years ago, and around 14 million years ago, the Ponginae (orangutans), diverged from the Hominidae family.

Charles Darwin:

• The possibility of linking humans with earlier apes by descent became clear only after 1859 with the publication of Charles Darwin's On the Origin of Species, in which he argued for the idea of the evolution of new species from earlier ones. Darwin's book did not address the question of human evolution, saying only that "Light will be thrown on the origin of man and his history".

Evidence:

• The evidence on which scientific accounts of human evolution is based comes from many fields of natural science. The main sources of knowledge about the evolutionary process has traditionally been the fossil record, but since the development of genetics beginning in the 1970s, DNA analysis has come to occupy a place of comparable importance.

Evidence from molecular biology:

• The closest living relatives of humans are bonobos and chimpanzees (both genus Pan) and gorillas (genus Gorilla).With the sequencing of both the human and chimpanzee genome, current estimates of the similarity between their DNA sequences range between 95% and 99%

Evidence from fossils

• There is little fossil evidence for the divergence of the gorilla, chimpanzee and hominin lineages. The earliest fossils that have been proposed as members of the hominin lineage are Sahelanthropus tchadensis dating from 7 million years ago, Orrorin tugenensis dating from 5.7 million years ago and Ardipithecus kadabba dating to 5.6 million years ago.

Use of tools:

• The use of tools has been interpreted as a sign of intelligence, and it has been theorized that tool use may have stimulated certain aspects of human evolution, especially the continued expansion of the human brain. Paleontology has yet to explain the expansion of this organ over millions of years despite being extremely demanding in terms of energy consumption.

A sharp rock, an Oldowan pebble tool, the most basic of human stone tools: