About 2 mya, fossils begin to appear from our own genus, Homo.Although several species of Homo are recognized, we will lump them all together for didactic purposes and refer to them as Homo erectus.Such an expense does not come without important evolutionary tradeoffs.Tags: Write An Essay On Right To Inion ActTeenage Pregnancy Research Proposal PaperThesis Questions ArchitectureSolving Limit ProblemsA Romance Thesis New York CityArgument Essay Topics For Middle SchoolMit Optional Essay Word Limit
The reasons behind the evolutionary increase in brain size are not known, although there is no shortage of speculation.
The need to fashion better tools, the requirements for sophisticated social interaction with conspecifics, the benefits of symbolic thought and language for competition between human groups have all been postulated as reasons for the intelligence of hominids.
Still, we are stuck in the present and must do the best we can with the available data.
Most biologists suspect that humans and chimpanzees split off from a common ancestor as recently as 4 to 5 million years ago. One of the first evolutionary developments that distinguish human ancestors from chimps was upright posture.
Over the course of 2 million years, several varieties and species of Australopithecines may have cohabited together and possibly even competed with one another in the savanna and woodlands that border the savanna.
Little is known about the behaviour of the Australopithecines other than they probably used tools and were a highly social species as chimps and we are today.
Metabolically, the brain is a very expensive organ.
Although it comprises only 2% of body weight, it consumes about 20% of the body’s metabolic resources.
The reason for the development of upright posture is unknown, but it certainly permitted the Australopithecines to travel long distances, freed their hands to carry objects, and may even have allowed more efficient thermoregulation.
Because of these advantages conferred by upright posture, many anthropologists suspect that the early Australopithecines were adapting to life on the savanna while the ancestors of today’s chimps remained in the forested areas of central Africa.