http://apologeticspress.org/APContent.aspx?category=9&article=985
Who Is This "Eve"?
| by | Trevor Major, M.Sc., M.A. |
A scientific “discovery” has captured the attention of the popular press. It seems scientists have “proven” that all modern human beings can trace their ancestry back to one woman living 200,000 years ago in Africa (Cann, et al., 1987). This one woman was nicknamed “Eve”—much to the media’s delight. An article in the January, 1987 issue of Time magazine was headed, “Everyone’s Genealogical Mother: Biologists Speculate that ‘Eve’ Lived in Sub-Saharan Africa” (Lemonick, 1987). A year later, that “speculation” became a major Newsweek production titled “The Search for Adam and Eve” (Tierney, et al., 1988). The provocative front cover presented a snake, tree, and nude African couple in a “Garden of Eden” setting. The Bible-story imagery was reinforced by showing the woman offering an apple to the man.
Many people latched onto these findings as proof of the biblical record. After all, didn’t they prove what the Bible has always taught—that Eve was the first woman? Others have seen the story for what it is: media hype over a new twist in evolutionary thinking encumbered with questionable assumptions. After some background discussion, several difficulties with the evolutionary “Eve” hypothesis will be presented.
MAKING OUR FAMILY TREE
Two questions come to mind in responding to the researchers’ claims described above. First, how can they say that our common ancestor was a woman living in Africa? And second, how can they say she lived around 200,000 years ago?
A FEMALE PREROGATIVE
The genetic material in the cell nucleus, with its DNA code, controls the functions of the cell, bringing in nutrients from the body, and making hormones, proteins, and other chemicals. Outside the nucleus is an area called the cytoplasm which contains, among other things, tiny bean-shaped objects called mitochondria. These are often described as the “energy factories” of the cell.
Mitochondria have their own DNA which is used to make some of the mitchondrion’s proteins; the nuclear DNA does the rest. The mitchondrial DNA (or mtDNA) is special for two reasons. First, it is short and simple in comparison to the nuclear DNA, containing only thirty-seven genes instead of around 30,000 genes. This makes it relatively easy to analyze. Second, unlike nuclear DNA, which we inherit in a jumbled, mixed-up form from both our parents, mitochondrial DNA is passed on through the mother’s line only. Apparently, either the sperm cell does not contain mitochondria, or it is somehow excluded when the sperm enters the egg. So, when the fertilized cell divides, each new cell will contain copies of the egg’s mitochondria. Even if we look the “spitting image” of our father, every cell in our bodies is supposed to contain our mother’s mitochondrial DNA.
In trying to draw up the human family tree, therefore, researchers have taken a special interest in these minute strands of genetic code. What they are really interested in, however, is the variations in mitochondrial DNA from one group of people to another.
THE DAUGHTERS ARE TESTED
Although our mitochondrial DNA is probably the same as our mother’s mitochondrial DNA, small changes or mutations in the genetic code can arise. On rare occasions, mutations are serious enough to do harm. More often, however, the mutations have no effect on the proper functioning of the DNA or the mitochondria. In these cases, the changes will be preserved, and carried on through the female line to succeeding generations.
If we look further and further into the past, we will find that the number of women who contributed the modern varieties of mitochondrial DNA get less and less until, finally, we get to one “lucky” mother. She would be the only woman out of all the women living in her day to have a daughter in every generation till the present. Coming forward in time, we would see that the mitochondrial DNA varieties of her female contemporaries were gradually eliminated as their daughters did not have children, had only sons, or had daughters who did not have daughters. This doesn’t mean to say that we look like this ancestral mother, only that we all get our mitochondrial DNA from her.
To find this woman, researchers compared the different varieties of mitochondrial DNA in the human family. As mitochondrial DNA occurs in small quantities, and the researchers wanted a large sample from each person, they decided to use human placentas. So Rebecca Cann and her colleagues selected 145 pregnant women and two cell lines representing the five major geographic regions: 20 Africans, 34 Asians, 46 Caucasians, 21 aboriginal Australians, and 26 aboriginal New Guineans (1987, p. 32). All placentas from the first three groups came from babies born in American hospitals. Only two of the 20 Africans were born in Africa.
After analyzing a portion of the mitochondrial DNAin the cells of each placenta, they found that the differences grouped the samples by region. In other words, Asians were more like each other than they were like Europeans, New Guineans more like each other than they were like Australians, and so on.
Next, they saw two major branches in their computer-concocted tree of recent human evolution. Seven African individuals form one distinct branch that starts lower on the trunk than the other four. This is because the differences among these individuals are much greater than the differences between other individuals and other groups. More differences mean more mutations, and hence more time to accumulate those changes. If the Africans have more differences, then their lineage must be older than all the others. The second major branch bears the non-African groups and, significantly, a scattering of the remaining thirteen Africans in the sample. To the researchers, the presence of Africans among non-Africans meant an African common ancestor for the non-African branches which, likewise, meant an African common ancestor for both branches. The nickname “Eve” stuck to this hypothetical common ancestral mother, and later fired the media’s imagination.
“EVE’S” BIRTHDAY
Having concluded that the African group was the oldest, Cann and her colleagues wanted to find out how old. To do this, they used what is known as a molecular clock based, in this case, on mutations in mitochondrial DNA. The rate at which the clock is ticking is determined from the accumulation of changes over a given period of time. So if two groups had a common ancestor 100,000 years ago, and if there is 0.2% difference in their genetic code, and if the rate of mutation is constant, then the rate of change is 0.2% per 100,000 years (or 2% every million years).
The researchers looked in two places for their figures. First, they compared mitochondrial DNAfrom humans with chimpanzees, and used paleontology and other molecular clock data to determine the age of the common ancestor. This, and similar calculations on other species, revealed a mutation rate in the range 2% to 4% per million years. Second, they compared groups in their study that were close geographically, and took the age of the common ancestor from estimated times of settlement as indicated by anthropology and archaeology. Again, 2% to 4% every million years seemed reasonable to them.
As the common mitochondrial ancestor diverged from all others by 0.57%, she lived sometime between approximately 140,000 (0.57 ÷ 4 × 1,000,000) and 290,000 (0.57 ÷ 2 × 1,000,000) years ago. The figure of 200,000 was chosen as a suitable round number.
THEORIES OFFERED
The results obtained from analysis of mitochondrial DNA led to the “Out of Africa” theory. It is the idea that the descendants of mitochondrial “Eve” were the only ones to colonize Africa and the rest of the world, supplanting all other hominid populations in the process. If the descendants of Homo erectus groups living in China had mixed with their African counterparts, for example, then a distinct Asian branch would emerge on the tree. However, no other groups show as much variety as the African mitochondrial DNA pool. Further, if non-African females did not contribute any mitochondrial DNA, then it is possible that non-African populations did not contribute any nuclear DNA either. Evolutionists claim that such an interpretation is in accord with archaeologic, paleontologic, and other genetic data (Stringer and Andrews, 1988).
While many have accepted the mitochondrial DNA tree, they differ on the source of nuclearDNA and the humanity of “Eve.” Some believe she contributed all the nuclear DNA in addition to the mitochondrial DNA. Some believe she was an “archaic” Homo sapiens, while others believe she was fully human. The exact interpretation is debated because mitochondrialDNA is “something of a passenger in the genetic processes that lead to the formation of new species: it therefore neither contributes to the formation of a new species nor reveals anything about what actually happened” (Lewin, 1987, p. 24).
PROBLEMS WITH MITOCHONDRIAL “EVE”
Rebecca Cann and her colleagues obtained 145 placentas, extracted the mitochondrial DNA, analyzed certain portions of the genetic code, and used a computer program to derive the simplest or most parsimonious solution. All this work was carried out with assumptions, many of which are open to criticism on a scientific basis. Most important, their mitochondrial “Eve” is totally different from the biblical Eve; it is impossible to reconcile the two.
(1) Perhaps the most obvious problem relates to the molecular clock used to date the branches of “Eve’s” “family tree” and the appearance of “Eve” herself. Even those involved in the research are uncertain about the assumption of rate constancy. In addition, the “calibrations” of the clock are based on archaeology and paleontology, and involve a reliance on radiometric dating methods, evolutionary interpretations of the fossil record, and evolutionary views of cultural and social development.
(2) Evolutionists place “Eve” in a sequence of developing creatures. Depending on the model used, her ancestors may have been fully human, or an “archaic sapiens species” derived from an African population of Homo erectus. However, the true biblical Eve was the first woman; there were no preceding human or “sub-human” species. Adam called his wife Eve, because she was the mother of all the living (Genesis 3:20). Further, modern humanity owes its characteristics to the three sons of Noah and their wives; the genetic information of all others perished in the Flood. Thus, the most recent common mitochondrial forebear of all people living today would be the common female ancestor of Noah’s three daughters-in-law (this woman may have been Eve herself).
(3) Some objections surround the selection of contributors to the mitochondrial DNA sample. As many of the samples came from representatives of ethnic groups living in the U.S., there is a chance that the mitochondrial DNA may have been modified by intermarriages with other groups on the American continent. This limitation was supposedly overcome by excluding any pregnant woman whose family history involved cross-cultural mixing. Cann considered this screening process successful because most of the black Americans shared many mitochondrialDNA attributes with the African-born individuals. However, the possibility of genetic mixing is not eliminated altogether, in which case the results may change with a different sample set. This was the case for researchers at Emory University in Atlanta who, in conducting mitochondrialDNA research, took samples from 700 people on four continents. They also concluded that mitochondrial “Eve” originated around 200,000 years ago, but they suggested the place may have been Asia, rather than Africa. It should be noted that the biblical Eve originated not in Africa or Asia, but in the Garden of Eden—a place no longer in existence owing to the destructive force of the Noachian flood (Bromling, 1989).
(4) As with nuclear DNA, there are questions concerning both the theory and the actual mechanics of the experimental process. For example, is the process of accumulating mutations understood sufficiently? Does the technique assess an adequate proportion of codes along the mitochondrial DNA? Can mitochondrial DNA comparisons be used to indicate family relationships over long periods of time, or are there other complicating factors which would limit such use? These issues arise frequently in the scientific literature, although they are often dismissed as temporary gaps in knowledge. However, research is proceeding as if these answers will do nothing but vindicate the latest findings. Evolutionists derive some solace from their interpretation of the fossil record, which is used to confirm the assumptions and conclusions used in theories of molecular evolution. Such circular reasoning severely limits an unbiased consideration of the data.
(5) Lastly, other scientists find the popular “Out of Africa” interpretation unrealistic. Is it reasonable to expect a population to spread out over the whole world without ever interbreeding with other people? According to Milford Wolpoff of the University of Michigan, “In recorded history, there has always been intermixing as populations moved or villages exchanged wives. I believe we have a long history of people constantly mixing with one another and cooperating with one another and evolving into one great family” (quoted by Tierney, 1988, p. 51). Thus, if the interpretation requires special pleading (i.e., that no interbreeding occurred), then this may throw doubt on the method itself.
CONCLUSION
Who is this “Eve”? She is a hypothetical creature living tens of thousands of years ago; she allegedly lies somewhere in the evolutionary line of descent from Homo erectus to Homo sapiens sapiens; and she is the supposed source of all the varieties of mitochondrial DNA found in the world today. But she is not the Eve of Scripture; she is not the first female to be made in the image of God; she is not the woman created especially for Adam; and she is not the mother who bore Cain and Abel. The mitochondrial “Eve” issue is a good example of how the media can sensationalize a highly tenuous theory. To them, references to Eve and the Garden provide that additional twist to capture the public’s imagination, its attention, and thus its money. Upon further examination, calling this common ancestor “Eve” turns out to be a slap in the face of those people who respect the Word of God. Rather, ample valid scientific evidence exists to show the truth of human origins without having to embrace speculative and unscriptural ideas.
REFERENCES
Avise, John C. (1989), “Nature’s Family Archives,” Natural History, pp. 24-26, March.
Bromling, Brad T. (1989), “Will Eden Ever Be Found?,” The Restorer, 9[2]:6-7, February.
Cann, Rebecca L., Mark Stoneking, and Allan C. Wilson (1987), “Mitochondrial DNA and Human Evolution,” Nature, 325:31-36, January 1.
Denton, Michael (1985), Evolution: A Theory in Crisis (Bethesda, MD: Adler and Adler).
Edey, Maitland A. and Donald C. Johanson (1989), Blueprints (Boston: Little, Brown).
Gibson, L.J. (1987), “Do DNA Distances Reveal Avian Phylogeny?,” Origins (Loma Linda, CA: Geoscience Research Institute), 14[2]:47-76.
Kirsch, John A.W. and Carey Krajewski (1988), “Letters: Conflict Over the Molecular Clock,”Science, 242:1624, December 23.
Lemonick, Michael D. (1987), “Everyone’s Genealogical Mother,” Time, p. 66, January 26.
Lewin, Roger (1987), “The Unmasking of Mitochondrial Eve,” Science, 238:24-26, October 2.
Lewin, Roger (1988a), “Conflict Over DNA Clock Results,” Science, 241:1598-1600, September 23.
Lewin, Roger (1988b), “DNA Clock Conflict Continues,” Science, 241:1756-1759, September 30.
Major, Trevor and Bert Thompson (1986), “Evolution, Creation, and the Fossil Record—[Parts I-III]” Reason & Revelation, 6:27-38, July/August/September.
Stringer, C.B. and P. Andrews (1988), “Genetic and Fossil Evidence for the Origin of Modern Humans,” Science, 239:1263-1268, March 11.
Tierney, John, Lynda Wright, and Karen Springen (1988), “The Search for Adam and Eve,”Newsweek, pp. 46-52, January 11.
AUTHOR’S POSTSCRIPT, 1992
Research that purports to confirm Cann’s findings has appeared in the years since my article was published (e.g., Vigilant, et al., 1991). Meanwhile, Milford Wolpoff and others have continued to pit their fossils against the molecular data (see the debate in the April 1992 issue of Scientific American). More important, various geneticists have criticized the statistical basis of the “Eve” hypothesis. They have shown that other trees with non-African roots are possible, but that the variation among these computer-generated solutions is so great as to negate any conclusions about human evolution that might be based on mitochondrial DNA (e.g., Templeton, et al., 1992).
Templeton, A.R., S.B. Hedges, S. Kumar, and K. Tamura (1992), “Human Origins and Analysis of Mitochondrial DNA Sequences,” Science, 255:737-739, February 2.
Vigilant, Linda, et al. (1991), “African Populations and the Evolution of Human MitochondrialDNA,” Science, 253:1503-1507, September 27.