Skip to main content icon/video/no-internet
icon backReturn to Entries

Homo Sapiens

Age of Homo sapiens

The Homo sapiens lineage may be as old as500,000 years. Although the oldest fossil remains only date to about200,000 years, there is growing evidence that the H. sapiens lineage may be much older. Assuming that H. neandertalensis is its own species (and evidence for this assumption grows), then the last common ancestor of both terminal species of hominoid evolution may have lived around that time. Paleoanthropology has not yet sufficiently resolved the taxonomic status of earlier Homo fossils such as H. antecessor (more than 800,000 years from Spain), which might as well be a grade as H.heidelbergensis. The oldest Neandertal lived at least250,000 years ago.

A caveat of paleoanthropology and the reconstruction of the evolutionary history of H. sapiens is first the decoupling of fossilized information (such as skull anatomy)from the crucial processes (sexuality, social organization, cognition, cultural evolution) in H. sapiensevolution. And second, the transition from archaic sapiens to modern sapiens was a continuous process.

Scenarios of Hominization

For quite a while, two contrasting models, the “out-of-Africa hypothesis” and the “multiregional hypothesis” and their modifications, dominated the discussion of the origin ofH. sapiens. The out-of-Africa hypothesis(synonym, “Arche Noah-model,” “replacement hypothesis,”“Eve-hypothesis,” or “Lucky-Mother–hypothesis”) assumes a common origin of all modern humans in Africa and thus that their morphological divergence of all recent human population is the result of a relatively recent differentiation. According to the “multiregional hypothesis” (or “candelabrum model”), modern human populations are derived from regional precursor populations, and Asians and Europeans are thus descendants of earlier endemic humans. The “assimilation model” tries to reconcile both diametrically opposed hypotheses, assuming a somewhat “mixture” of modern immigrants with endemic populations. Very recent findings even suggest a genetic bottleneck more the 50,000 years ago, which would even more contradict a multiregional origin of all modern human populations.

The discussions in all models are limited to the last 150,000 years of H. sapiens evolution.

The Fossil Record

The indisputable fossil record of H.sapiens actually starts in Ethiopia with the specimens Omo I and Omo II from the Kibbish formation now dated at 195,000years, followed by H. sapiens idalto from Afar, Ethiopia (160,000 years), and by the remains from Border Cave, South Africa (> 100,000 years). Evidence gathered from both molecular genetics (for example, mitochondrial genes)and linguistics support an African origin of all modern humans. This does not necessarily imply that the origin of early sapiens is also found in Africa.

Short-term climatic changes in the Pleistocene led to a habitat fragmentation in Africa. The cooling effect of the climate change fragmented forests, whereas the warming effect expanded savannahs. Humans, by having to react to these relatively short-term climatic alterations, learned to adapt to changing environments. This later enabled their universal dispersal (not to be confused with migration) seen in no other mammalian species. Occurrence of H. sapiens outside Africa is documented as being younger than 100,000 years in the Middle East (Shkul V, Israel, 90,000 years; Qafzeh IX, Israel,90,000–100,000 years). Note that recent redating of the sites contradicts a simple succession of Neandertal and modern humans. The dispersal out into the rest of the world started more than 60,000 years ago. Humans reached Asia about 60,000years ago, Australia around 50,000 years ago, Europe40,000–35,000 years ago (“Cro magnon”), and America 35,000–15,000 years ago. The splitting of human ethnic groups is also documented by a similar splitting of their parasitic bacterium, Heliobacter pylori,into various subgroups.

...

  • Loading...
locked icon

Sign in to access this content

Get a 30 day FREE TRIAL

  • Watch videos from a variety of sources bringing classroom topics to life
  • Read modern, diverse business cases
  • Explore hundreds of books and reference titles

Read next

More like this

Sage Recommends

We found other relevant content for you on other Sage platforms.

close

Have you created a personal profile? Login or create a profile so that you can save clips, playlists and searches

close
close
close Signed In to profile You are signed in as:
close
Logged in Institution Institution