1650 words

Ever since Chris Stringer and Peter Andrews (1988) discovered that the genetic and archaeological evidence confirms OoA, there has been uproar in some of the less intellectually inclined and ideological sects of the Internet. These people emphatically deny—without evidence (using their emotions like a leftist, ironic…)—that the OoA hypothesis is wrong, because ‘I can’t be related to Africans, my skin is white and theirs is black—black skin cannot turn white!’ (one of the more ridiculous statements I’ve come across in my time). The fact of the matter is, people who deny OoA have ideological reasons to do so, which are not backed by science. I will provide the best (and most recent) data pointing to the OoA hypothesis, as well as go through the main paper that OoA-deniers may bring up.

OoA was first proposed by archaeologist Christ Stringer in the late 1980s (Stringer and Andrews, 1988). The totality of genetic and archaeological evidence points to Africa as the home for Anatomically Modern Humans (AMH). One of the best points of evidence is that Africans have the highest level of genetic diversity amongst humans on the planet (Campbell and Tishkoff, 2008; Gomez, Hirbo and Tishkoff, 2014; Ashraf and Galor, 2014). Furthermore, Tattersall (2009) showed that a “radical reorganization of gene expression that underwrote the distinctive physical appearance of H. sapiens was probably also responsible for the neural substrate that permits symbolic cognition.” Here are the first signs of behavioral modernity that PumpkinPerson speaks about. What people do not understand (nor grasp), is that most of our modern-day behaviors originated in Africa (see comments by Jm8 here).

Proving OoA, nowadays, is pretty ‘easy’. I say ‘easy’, because nothing ever really gets ‘proven’ in science; as any theory can be uprooted when new evidence is available. However, there are a few key data points that point to OoA being a fact:

Melanesians and Australoids share genetic affinities linked to the OoA exodus 50kya. OoA was only really in dispute due to the lack of AMH fossil evidence in Melanesia/Australia (at the time of the exodus they were a conjoined landmass (the landbridge becoming submerged underwater around 8kya). Minor secondary gene flow into the area, but after the disappearance of the land bridge, they became more homogeneous. So any differences in the archaeological record are due to isolation from the landbridge disappearing. Hudjasov et al (2007)

Further, genetic evidence also attests to the appearance of AMH in Africa. Nei (1995) provides evidence that AMH arose 100-200 kya with all humans alive today being descendants of migrations that began ~100 kya (around 70 kya). Further, since genetic diversity decreases as the distance from Africa increases shows the OoA hypothesis to be true. Bottlenecks and founder effects reduce genetic diversity. There is also recent data that suggests that the population bottleneck coming OoA along with deleterious alleles that introgressed from Neanderthal to Eurasians caused a 1 percent decrease in historic fitness respectively (Harris and Nielson, 2016). This is further evidence that AMH began in Africa: the main piece of evidence is the population bottleneck. Since population bottlenecks and founder effects reduce genetic diversity, and the further you go from Africa, more and more populations show less and less genetic diversity from Africans, this is one major clue.

Furthermore, a human skull discovered in South Africa further attests to the truth of OoA. This skull shows similarities with skulls found in Europe at that same time period; predicting that AMH would have been found in Europe about 40 kya. This is true, and yet another piece of evidence for the OoA hypothesis. Why would two skulls separated by tens of thousands of miles be similar? Because they have the same origins, obviously.

For a solid review of the OoA hypothesis vs. the multiregional hypothesis see Edwards (2012). The preponderance of evidence points to Africa as the origin for AMH. (This article will be frequently updated with new information).

OoA Denial

Referring back to what I stated at the beginning of this piece, many people will deny OoA due to ideological reasons. When they hear of people pushing (what is currently archaeologically/genetically true) OoA, they get upset. “How could I be descended from people with dark skin, I am white!” Clearly, people don’t understand the mechanisms of evolution, nor how people adapt to climate through natural selection (obviously drift, migration and mutation plays a role here as well). I will present and go through two pieces of ‘evidence’ that OoA deniers cite when attempting to show the OoA hypothesis wrong.

No, Not Africa, RUSSIA!

This one is ridiculous. It is also the most cited study from OoA deniers. In 2012, researchers Klyosov and Rozhanskii reportedly ‘debunked’ the OoA hypothesis. Their most major claims are: AMH arose on the ‘Russian plain’ which extends from Russia to Germany and France (WOW what a huge ground for them! Seems like he ‘posited’ this large area so he ‘may be right by chance—a fat chance); that the AMH spoke a proto-Slavic language (….); Indo-Europeans being synonomous with Slavs etc. It’s ridiculous. A comment from the abstract of the article:

The earliest anatomically modern humans outside Africa and the Middle East very close to Africa, (there are some 100,000 year old specimens in Israel), are 60,000 years old-and they didn’t come near Russia. The next oldest anatomically modern humans in Europe and most of Asia are 46,000 years old. So the very concept of the first anatomically modern humans first coming into being in Russia is hilarious.

And now we have this article: Jewish-Academic subversive, malicious ‘Out of Africa Hypothesis’ annihilated which uses the Kysolov study, as well as misrepresenting another in order to ‘prove’ that the OoA hypothesis is false.

One of the largest claims he makes is that Kysolov’s paper proves there is no link to Australia from Africa. However, Hudjasov (2007) showed that Melanesians and Australoids do show affinities to Africans.

His main point is that it’s not Out of Africa—it’s Out of Australia. “Humans weren’t one coherent group”, except Homo Sapiens dispersed OoA, spreading maternal haplotype L3 all around the world between 50,000-100,000 ya (Moreno, 2011; Pagani et al, 2015; Stock, 2008; Klein, 2009). The dispersal of the L3 haplogroup confirms OoA (Rito et al, 2013).

Finally, we have the evolution of white skin. The allele that codes for white skin, SLC24A5, evolved around 7500 ya (Malick et al, 2013). This allele has the greatest effect on skin color in Europeans and neighboring populations (Cochran and Harpending, 2009). This throws a wrench into that theory; the phenotypes we racially code are recent (Mathieson et al, 2015). This is why peoples can ‘look similar’ despite being geographically separated: because the races we see today are new. Europeans are an amalgamation of three populations: the Yamna, West-European hunter-gatherers and Anatolian Farmers. I’m not saying that racial categories aren’t meaningful; just saying that they’re recent (which attests to the recent how fast racial differences have been occurring). Furthermore, faster evolution means more racial differences due to genetic isolation.

In sum, the preponderance of evidence points to Africa as being the birthplace of AMH. People can deny it for ideological reasons due to ignorance of how the evolutionary process works, but just because people don’t believe something doesn’t mean it’s not true. In my opinion, one of the best pieces of evidence for the dispersal of Man out of Africa is, as Darwin first noticed, apes and gorillas evolved in Africa. It’s only logical to posit that Man also evolved in Africa, from a primate with a common ancestor. Multiregional hypotheses don’t make sense with the genetic data.

References

Ashraf, Q., & Galor, O. (2011). The “Out of Africa” Hypothesis, Human Genetic Diversity, and Comparative Economic Development. doi:10.3386/w17216

Campbell, M. C., & Tishkoff, S. A. (2008). African Genetic Diversity: Implications for Human Demographic History, Modern Human Origins, and Complex Disease Mapping. Annual Review of Genomics and Human Genetics,9(1), 403-433. doi:10.1146/annurev.genom.9.081307.164258

Cochran, G., & Harpending, H. (2009). The 10,000 year explosion: how civilization accelerated human evolution. New York: Basic Books.

Edwards, S. (n.d.). (2012) ANTHROJOURNAL Analysis of Two Competing Theories on the Origin of Homo sapiens sapiens: Multiregional Theory vs. the Out of Africa 2 Model. Retrieved February 08, 2017, from http://anthrojournal.com/issue/october-2011/article/analysis-of-two-competing-theories-on-the-origin-of-homo-sapiens-sapiens-multiregional-theory-vs-the-out-of-africa-2-model

Gomez, F., Hirbo, J., & Tishkoff, S. A. (2014). Genetic Variation and Adaptation in Africa: Implications for Human Evolution and Disease. Cold Spring Hanrbor Perspectives in Biology,6(7). doi:10.1101/cshperspect.a008524

Harris, K., & Nielsen, R. (2015). The Genetic Cost of Neanderthal Introgression. Genetics, 2016 doi:10.1101/030387

Hudjashov, G., Kivisild, T., Underhill, P. A., Endicott, P., Sanchez, J. J., Lin, A. A., . . . Forster, P. (2007). Revealing the prehistoric settlement of Australia by Y chromosome and mtDNA analysis. Proceedings of the National Academy of Sciences,104(21), 8726-8730. doi:10.1073/pnas.0702928104

Klein, R. G. (2009). Darwin and the recent African origin of modern humans. Proceedings of the National Academy of Sciences,106(38), 16007-16009. doi:10.1073/pnas.0908719106

Klyosov, A. A., & Rozhanskii, I. L. (2012). Re-Examining the “Out of Africa” Theory and the Origin of Europeoids (Caucasoids) in Light of DNA Genealogy. Advances in Anthropology,02(02), 80-86. doi:10.4236/aa.2012.22009

Mathieson, I., Lazaridis, I., Rohland, N., Mallick, S., Patterson, N., Roodenberg, S. A., . . . Reich, D. (2015). Genome-wide patterns of selection in 230 ancient Eurasians. Nature,528(7583), 499-503. doi:10.1038/nature16152

Nei, M. (1995). Genetic support for the out-of-Africa theory of human evolution. Proceedings of the National Academy of Sciences,92(15), 6720-6722. doi:10.1073/pnas.92.15.6720

Mallick, C. B., Iliescu, F. M., Mã¶Ls, M., Hill, S., Tamang, R., Chaubey, G., . . . Kivisild, T. (2013). The Light Skin Allele of SLC24A5 in South Asians and Europeans Shares Identity by Descent. PLoS Genetics,9(11). doi:10.1371/journal.pgen.1003912

Moreno, E. 2011. The society of our ‘out of Africa’ ancestors (1). Communicative & Integrative Biology, 4, 163e170

Pagani, L., Schiffels, S., Gurdasani, D., Danecek, P., Scally, A., Chen, Y., . . . Tyler-Smith, C. (2015). Tracing the Route of Modern Humans out of Africa by Using 225 Human Genome Sequences from Ethiopians and Egyptians. The American Journal of Human Genetics,96(6), 986-991. doi:10.1016/j.ajhg.2015.04.019

Rito, T., Richards, M. B., Fernandes, V., Alshamali, F., Cerny, V., Pereira, L., & Soares, P. (2013). The First Modern Human Dispersals across Africa. PLoS ONE,8(11). doi:10.1371/journal.pone.0080031

Stock, J. T. (2008). Are humans still evolving? Technological advances and unique biological characteristics allow us to adapt to environmental stress. Has this stopped genetic evolution? EMBO reports,9. doi:10.1038/embor.2008.63

Stringer, C., & Andrews, P. (1988). Genetic and fossil evidence for the origin of modern humans. Science,239(4845), 1263-1268. doi:10.1126/science.3125610

Tattersall, I. (2009). Human origins: Out of Africa. Proceedings of the National Academy of Sciences,106(38), 16018-16021. doi:10.1073/pnas.0903207106