Deciphering the human genome: what does it mean?
Published: 3 February 2006 (GMT+10)
9 March 2001
The media gave extraordinary attention to the recent publication of the draft sequence of the human genome by two teams of researchers in two leading scientific journals.1,2 Some dubbed it ‘the biggest news event in the past 50 years of science’. And it certainly is a monumental achievement.
Many headlines proclaimed it as a ‘breakthrough’ that would revolutionize medicine. Some commentators questioned whether this knowledge would be to the benefit or detriment of society, now that employers and medical insurers would have the potential to discriminate against people with ‘bad’ genes.
Most of the electronic news media said that humans are not as complex as first thought—with only around 35,000 genes (previous estimates had ranged up to 140,000), i.e. we have roughly the same number of genes as an ear of corn, or only twice as many as a fruit fly.
But one commentator, criticising the rest of the media for missing ‘the most basic, the most important consequence of mapping out all of our genes’ wrote under the headline of ‘Darwin vindicated!’:3
‘The genome reveals, indisputably and beyond any serious doubt, that Darwin was right—mankind evolved over a long period of time from primitive animal ancestors.’
And just to make sure that no-one would miss his real message, he continued:
‘Our genes show that scientific creationism cannot be true. The response to all those who thump their bible [sic] and say there is no proof, no test and no evidence in support of evolution is, “The proof is right here, in our genes.” … There is, as the scientists who cracked the genome all agreed, no other possible explanation. … The theory of evolution is the only way to explain the arrangement of the 30,000 genes and three billion letters that constitute our genetic code. … Those who dismiss evolution as myth, who insist that evolution has no place in biology textbooks and our children’s classrooms, are wrong.’
The writer, Arthur Caplan Ph.D., is director of the Center for Bioethics at the University of Pennsylvania. However, it will become apparent that such claims are little more than brash hand waving, having no basis in fact. First of all, there are two obvious philosophical points:
If it’s only now that Darwinism has been proven and Biblical Creation disproven, then how was it previously possible to claim these very things? Previous ‘proofs’ of evolution and ‘disproofs’ of creation, e.g. melanism in the peppered moths, Haeckel’s embryonic drawings ‘proving’ recapitulation and similarity, life from the Martian meteorite, have turned out to be nothing of the kind. But their retraction never has the same publicity.
If materialism is accepted a priori, before examining the evidence, then evolution is the only game in town (see The belief system behind evolution). So by definition, anything is proof of evolution, even mutually contradictory states of affairs.
Number of genes
It is certainly true that humans have far fewer genes than expected. But media proclamations that we are not much more complicated than baker’s yeast are very misleading,4 as is the superficial equation that we are only twice as complicated (twice as significant?) as a fruit fly. More detailed news reports went on to quote the genetic researchers’ admissions that the relatively low number of genes means that the human genome ‘is a lot more complicated than we thought.’
How so? Because it used to be thought that for the most part, each gene contained the instruction code for building one specific protein (e.g.. a specific structural component of the cell). But now there is a mystery as to how only around 35,000 genes can direct the production of the hundreds of thousands of components that together make up a human body.
The answer seems to be hidden in the way that genes are ‘read’. Just as lots of different sentences could be strung together with only a limited number of ‘words’, so each gene can be read in combination with other genes to produce ten or more different proteins, according to what the body needs. (An analogy would be where a hypothetical set of instructions for manufacturing a radio could be read differently so as to provide the instructions for making a television, a mobile phone, a CD player or a DVD player, all obtained by selecting a different order of words/sentences. However, what determines how the instructions are read in the DNA to produce the different products is largely unknown). As the genetic researchers concede, mapping the letter sequences of the genes is not the same as being able to interpret the genetic code—and given that it is much more complex than they thought, this will take many years yet. In one sense, the easy part has been done, and that was a monumental task. Now the hard work begins!
The irony, of course, is that the genetic sequences, believed by evolutionists to have resulted from mere chance and natural selection, should be so hard to decipher, despite the continuing attention of so many of the world’s most brilliant scientists.
As researchers unravel the genome, their previous conceptions are themselves unravelling, for research is (as we predicted in a recent article, The Human Genome Project: how should we view it?) uncovering new layers of complexity that confound accepted ideas of how genes work. For example, it was thought that the instruction code for building a protein is ‘written’ on one strand of the double-stranded DNA molecule. But researchers recently identified a fruit fly protein whose instructions are provided by both strands of the DNA, which ‘raises new questions regarding genome complexity and evolution.’5
‘scientists have discovered many riches hidden in the junk, and … several researchers predict that some of the most intriguing discoveries may come from areas once written off as genetic wastelands.’7
For example, researchers have already found that among the ‘non-coding’ DNA there are crucial promoter sequences which control when a gene is turned on or off.
It also appears that areas of DNA previously dismissed as ‘barren’ actually contain sequences that play a crucial role in the process that inactivates one of the two X chromosomes in a female’s early development. These regions apparently contain hundreds of genes, says one researcher, who concedes that “The term ‘junk DNA’ is a reflection of our ignorance.”7 [See more articles about ‘Vestigial’ DNA]
We are only just scratching the surface with our knowledge of the human genome, so it is rather premature to be claiming that what we know confirms evolutionary ideas. It is, for instance, not at all unlikely that, even though most of the sequence is now known, there may be many more—maybe even thousands more—actual genes to be elucidated. Neither of the two teams that sequenced the DNA is sure of just how many genes there are—one team predicts that there are 31,000, the other predicts 39,000.
Genes from germs?
Some reports have said that we carry genes that were inserted by an ancient bacterium into the gonads of a distant ancestor. The same gene is now performing a different function in us than in that bacterium. But of course it is pure conjecture that this bacterial DNA transfer actually happened. The raw fact is simply that the same DNA sequence does one job in one of today’s bacteria, and another in humans. (And that’s nothing new; it’s old hat that certain genes in yeasts are not only found in humans, but have a different function.) In fact, such findings are:
Not a prediction of classical evolution theory.
Require some mind-boggling rationalizations (try to imagine how such a radical shift of function could take place, all the while maintaining functionality so that natural selection could ‘direct’ the change of function!).
Much more easily explained as mosaic design features. If the same base sequence can do a different job, why not? It is almost as if such things were created as barriers to an evolutionary explanation, for those able to step back from the evolutionary conditioning of our culture to see the ‘big picture’ (see Are look-alikes related? and The Biotic Message (below, right)).
So what else could have inspired such pronouncements about the genome proving evolution? It can hardly be based on detailed comparisons with the sequences of other organisms, because almost none of these are known. Even the genome of our alleged closest evolutionary relative, the chimpanzee, is largely unmapped.
CMI’s scientists actually await future gene-mapping results with great interest and anticipation, because evolutionary theory has a track record here already, and it is rather dismal. For instance, we do know the genetic sequences of a few groups of bacteria. Beforehand, it had been confidently predicted that these would reveal a pattern pointing back to a single common ancestor as expected by evolutionists. But the results have largely confounded the predictions and in trying to make sense of them within an evolutionary framework, researchers have postulated that different species must have somehow swapped genes (‘horizontal transfer’). Others have said that the only way to explain them is to assume that life arose independently several times. This is a bitter pill for them to swallow, because trying to explain life by chance once is impossible enough, given the known laws of science [See the articles on Q&A:Probability and Origin of Life]. It is quite likely that when the genomes of higher organisms are better known, even more difficulties will arise for those trying to explain how the complex programs of life essentially wrote themselves.
- International Human Genome Sequencing Consortium, Initial sequence and analysis of the human genome. Nature 409(6822):860–921, 2001. [Return to text.]
- Venter, J.C. et al., The sequence of the human genome. Science 291(5507):1304–1351, 2001. [Return to text.]
- Caplan, A., ‘Darwin vindicated!’—Cracking of human genome confirms theory of evolution, 26 February 2001. [Return to text.]
- Just on the number of genes, yeast has about 6,000, only a fraction of the number in the human genome. [Return to text.]
- Labrador, M., Mongelard, F., Plata-Rengifo, P., Baxter, E.M., Corces, V.G., and Gerasimova, T.I., Protein encoding by both DNA strands. Nature 409(6823):1000, 2001. [Return to text.]
- Wieland, C., The Human Genome Project: how should we view it?, 1st March 2001. [Return to text.]
- Vogel, G., Objection #2: Why sequence the junk? Science 291(5507):1184, 2001. [Return to text.]