The National Geographic Society has been running, in cooperation with others, a project to trace man’s origins according to ancestral markers found in DNA. Or more precisely, it has been studying mutations in the genetic codes (specifically in mitochondrial DNA and the Y-chromosome) of humans alive today to trace their origins and relationships backward, through the mists of time. The following map shows the general lines of distribution the study has revealed:
According to the study, modern man originated in Africa with an ancestral Adam and Eve about 150,000 years ago. Just as Genesis claims, we are all descended from a first coupling, or perhaps a number of first couplings, among the first group of modern humans, a clan or tribe of hunter/gatherers in Africa.
We weren’t content with life in Africa for long, from the National Geographic Magazine:
What seems virtually certain now is that at a remarkably recent date—probably between 50,000 and 70,000 years ago—one small wavelet from Africa lapped up onto the shores of western Asia. All non-Africans share markers carried by those first emigrants, who may have numbered just a thousand people.
This is an incredible tidbit of information, when one considers the geologic time scale at issue. According to the research, it took less than 70,000 years for the differences in environment to change a tall, lean, dark-skinned African into a squat, bulbous, light-skinned Inuit:
About the same time as modern humans pushed into Europe, some of the same group that had paused in the Middle East spread east into Central Asia. Following herds of game, skirting mountain ranges and deserts, they reached southern Siberia as early as 40,000 years ago.
The earth was entering its last ice age at about the same the time modern man began his dispersion out of Africa, so perhaps southern Siberia was as cold or colder than the Arctic is today, and natural selection started working its magical transformation as soon as man arrived in Asia. But still, 40,000 years is only time enough for about 2,000 generations of humans. The DNA study used the infrequency, but predictability, of genetic mutations to form genetic links amongst peoples. But the infrequency and unpredictability of favorable genetic mutation seems to be exactly what would make turning an African into an Inuit so difficult in such a short span of time.
Even more incredible is the narrative for how humans finally arrived in the Americas. The DNA evidence seems to reveal that they arrived fifteen to twenty thousand years ago via a Bering Sea land bridge, now submerged, that linked the continents due to low sea levels during the last ice age. But there is a glaring difficulty with this theory: How could any primitive human have been able to withstand such an extended journey into a frozen-white, barren abyss? During the last ice age, there may well have been a land bridge between Asia and North America, but so what? It would have been covered in ice year round, and the ocean around it locked in ice as well. It is a question scientists have grappled with extensively. It seems that the consensus is that an ice-free corridor opened in Canada around 13,500 years ago, but that’s not early enough, neither for the DNA evidence showing arrival 15-20 thousand years ago, nor for the mainly undisputed evidence that North America was populated as early as 16,000 years ago (the Meadow-croft Shelter in Pennsylvania) and South America as early as 14,000 years ago (Monte Verde in southern Chile).
Problems with the theory of human origins keep piling up. Perhaps taking stock of that which is known and that which is only speculated might be worthwhile:
*We know that all humans are of the same species, i.e., that a human of any of the variety of races is capable of mating with another human of a different variety and producing fertile offspring. In that regard, all humans everywhere are undeniably closely related, but being closely related says little about geographic origins.
*We know something of the rate at which human DNA mutates across populations, but have no way of knowing how durable these mutations are over time. These are early times so far as human DNA understandings go. A fair amount of what we think we know will likely be proven false if the learning curve for DNA is similar to that of other new discoveries or perspectives. History tells us there is great danger that new methods of understanding will first be put to use confirming old conclusions, which makes trusting conclusions drawn from the new method of understanding doubly suspect from the outset. Significantly, it seems that roughly 97% of the human genome is not used for coding proteins, the “junk” DNA. (This is eerily similar in ratio to the amount of the universe left unexplained by the theory of relativity; 96% of the universe is now believed to be dark matter and energy that we can’t detect; only 4% is believed to be the universe we know and can detect by our senses and sensory-extending equipment). We don’t know the purposes or origins of this junk DNA.
*We have a functional knowledge of the time between generations, i.e., we can calculate how many opportunities for genetic mutation have occurred over a span of time. A rough estimate for humans would be twenty years.
*We have a functional knowledge of the duration and extent of the last ice age.
*We don’t know how adaptive is human DNA, sans mutation, to allow phenotypic expression to vary according to environment; i.e., we don’t know how much, if any, of an African’s DNA needs to change, in order for him to become an Inuit, so we can’t know how long humans must have been in the Arctic for the transformation to take place. We do know that genotype generally determines phenotype (else natural selection and evolutionary theory would not work), and thereby must have some impact on the adaptation human populations have made to varying climates.
*We don’t conclusively know how humans made their way to the Americas, nor how long they have been here.
Thus, scientific theories of human origins float upon a fairly thin reed of evidence in a sea of speculation. Particularly troublesome is the patina of certainty regarding human origins founded on DNA analysis. It is impossible to know how frequently genetic mutations appear and disappear through time in the human population. We can know how frequently mutations appear across populations, but a human population is not an e. Coli bacteria culture, where several hundred generations of replication and its attendant mutations can be observed overnight. Without several hundred generations, or at least a great many more than we have, as to the particulars of human DNA mutation and evolution, any conclusions drawn on such a basis are fraught with speculation.
In fact, DNA analysis of the type the Human Genome Project is conducting is quite limited at deciphering a person’s genetic heritage, even assuming we have our estimations of mutation rates correct. For example, the DNA analysis of the Human Genome Project would not be able to tell whether I am one-quarter Cherokee Indian, as I have been told. My biological father, whom I don’t know and have never met, was purportedly a half-breed Cherokee Indian. His mother was supposedly Cherokee and his dad European, probably Scots-Irish or something similar, given the geography from which the union arose (North-Central Alabama). But there is no way a genetic analysis looking at mitochondrial DNA or the Y-chromosome could answer whether I, in fact, am one-quarter Cherokee. My paternal grandmother’s mitochondrial DNA was lost for me in the union of my mother and biological father. I inherited my mother’s mitochondrial DNA. My Y-chromosome came from my dad, but his came from his dad, who was European, etc. Nothing of the inquiry would tell, even one generation back, whether I had a Cherokee Indian grandmother. Don’t underestimate the limitations of DNA analysis in providing ancestral histories.
The question of origins is an ancient one. It resonates through the song line of the Aborigines and the folklore of the ancient Hebrews, Greeks and Romans, et al. Virtually every culture ever arisen or extant has created myths aimed at answering the question of origins, generally all of which aim to shape the past to create a cultural identity and purpose in the present and for the future. The Human Genome Project is no different in its aims. It clearly is biased to show that we all are related, such that the myths of ancient cultures conjuring differences amongst peoples can be obliterated. It wishes for us to overlook its biases for its exceptional methods of inquiry. Which is all fine and good. There is very little doubt that humans are all of the same species and share a common ancestor, even without DNA evidence or investigations. The fact that we can successfully breed with each other is all the evidence necessary to draw that conclusion. But the attempt to show a mish-mash of genetic history through DNA mutations contained in mitochondrial DNA and the Y-chromosome is perhaps carrying the point, and the science, too far.