Question

1. Describe the significant physical differences between H. ergaster and H. erectus and why you think they should be classified as one or two species.

Answer 1

1.9 million years ago some of the early transitional humans had evolved into a new fully human species in Africa.Most paleoanthropologists refers to them as Homo erectus.However a few researchers split them into two species Homo ergaster and Homo erectus.The ergaster fossils were presumably somewhat earlier and have been found for the most part in Africa.The erectus discoveries have been found widespread in Africa,Asia and Europe. H.ergaster could be the direct ancestor of H.erectus.There is obviously variation in bone structure between the two geographical regions,but as with modern humans,phenotypic variation can dramatically overexaggerate any real genetic differences as a whole.for example:modern humans only differ by around 0.1% of nucleotide diversity and the effective population for humans is near 10,000 individuals,compared to over 7.5 billion humans in the actual census population.yet no one would deny that ,despite such an insignificant difference in reality ,people still look pretty different depending largely on their geographical ancestry.This could have been the case with H.erectus as well.They may have had almost exactly the same genotype,only with differing phenotypes(this is usually not possible to observe in the fossilized bones themselves;it would require sequencing in tact genomes from both populations but DNA degrades over time.)

The earliest Homo erectus were contemporaries of the late Homo habilis in East Africa for several hundred thousand years.this suggests that the immediate ancestor of Homo erectus was an early Homo habilis or possibly another yet to be discovered species of early humans.Homo erectus was a very successful human species lasting at least 1.5 million years,though their numbers apparently remained relatevely low.some of them eventually evolved into our species ,Homo sapiens .That evolutionary transition was well under way by 400,000 years ago but was not complete until 200,000-100-000 years ago and possibly even later in some regions.