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Tuesday, September 01, 2009

Chimpanzees and Humans share a lot of genes: so what?

You may have read or heard that chimpanzees and humans share a lot of genetic material. The exact amount is not clear, but whether it's 97%, 99%, or something in between, doesn't really matter. It seems clear that our genetic material is quite similar, but, of course, not identical, to that of chimpanzees. So what?

There are, in fact, two different species of animals that have been called chimpanzees. One is Pan troglodytes, the other, first recognized as a separate species less than a hundred years ago, is Pan paniscus, the bonobo, sometimes called the pigmy chimpanzee. The fact that there are two species is not well understood by the general public.

Studies on the genetic diversity of chimpanzees and bonobos have been undertaken. See here and here for reports on one such study, from 1999. This research, based on a small portion of the DNA of chimpanzees, found that chimpanzees were more unlike each other than humans are. The report led at least some scientists to propose that humans were, as recently as 100,000 years ago, a very small population. (This is consistent with the descent of all humans from Adam and his family, and/or Noah and his family.)

A book reviewer in Spiked claims (based on a recent book that makes the same claim) that sharing 98.4% of our genes doesn't really make chimpanzees very human. The reviewer, and, apparently, the author (I have not read the book) say that much of that 1.6% is regulatory genes, which have profound effects, meaning, as it were, that humans and chimpanzees are less than 98.4% alike. (There is no way to quantify this, in reality, any more than, say, you could give an unambiguous quantitative answer to the question "How much like your spouse are you?")

For more on chimp DNA, see the Wikipedia article on the chimpanzee genome project. (Yes, there is such a thing. There are similar projects on several other organisms, each interesting in its own right.) That article says that 30% of human and chimp proteins are identical. (This doesn't necessarily mean that the DNA which coded for them is identical, as different combinations of DNA bases can lead to the same amino acid. It also doesn't mean that we are as much as 70% different from chimpanzees. It is likely that the differences between some of our proteins, compared to those of chimpanzees, are considerably less than 1%.)

Leaving aside the statistics, it is obvious to anyone that humans and chimpanzees are quite a bit alike. Facial expressions, body structure, and behavior show this. I have never read any credible source, from young-earth creationists to atheists, who would try to deny this similarity. No other animal, even gorillas and orangutans, seems to be so much like we are.

So what?

1) We did not descend from chimpanzees (or they from us). No reputable scientist believes that. Many reputable scientists believe that chimpanzees and humans share a common ancestor. Perhaps they are right, perhaps not.

2) Similarity does not prove that chimpanzees should be given the same rights as humans. A dead woman, or a convicted axe murderer, shares a lot of DNA with me, you, and President Obama. But neither of these should be given the right to vote, and one of them is not even alive, therefore they are not given the same rights as you, the President, and I. Chimpanzees, and other animals, should be cared for, under the God-given stewardship of human beings, and not treated cruelly, killed without reason, or deprived of their God-given habitat without very serious consideration. But they should not be given the right to hold office, or protected from killing at all costs. Early in Genesis, animals were killed for a cause, namely to provide clothing for Adam and Eve, by God Himself (Genesis 3:21). Also, in Genesis, animals were killed for another good reason, namely for sacrifices to God, which God accepted (Genesis 4:4).

(See here and here for posts on our responsibility for caring for nature.)

3) There are three possible reasons for the similarity between humans and chimpanzees.
One of them is that the two species have, indeed, come from a common ancestor.

The second is that God created the two species in separate creative acts, but chose to make them similar. (If that were the case, DNA similarity would cause and maintain other types of similarity.) A young-earth creationist would say that they were created a day or two apart. A believer in Intelligent design would say, I believe, that God designed them to be alike, even to using the same genes, or similar genes. A theistic evolutionist (this is too simple -- there are several categories of such) might say that God knew in advance what would happen, and designed the evolutionary mechanisms of living things so that humans would eventually come about, or that God took a pre-existing animal and specially endowed it with some special properties, that is, gave them a soul.

The third, which I don't think anyone really believes, is that the similarities are accidental.

4) Although we should understand that new findings may change scientific beliefs, we should also understand that there is a broad consensus among scientists about most of the fundamentals, in all fields of science, and Christians should not be anti-scientific. The consensus, for decades, has been that chimpanzees and humans share a common ancestor.
Just because there is consensus doesn't mean that the scientists are always right. There used to be consensus that protein was the genetic material, and that DNA wasn't. The consensus on the common ancestry of humans and chimps may also be wrong. The Bible seems to be unambiguous that humans are special -- Their origin is described separately, and in more detail, than that of all the other animals. They alone are singled out as being in the image of God. (Although, in some sense, all of His creation must have some of His image -- His characteristics.) Humans were given special responsibility for other organisms. To most Christians, this argues for a special creation of humans. I suppose most of them would suppose that God specially created them, body and soul, in one event. Some Christians (Billy Graham among them) are willing to accept that possibly God took a pre-existing human-like being, and endowed that creature with His image. (Graham is not wedded to that belief, but is willing to entertain the possibility, and doesn't believe that it would contradict scripture.) Science is never going to give clear answers on the origin of the God-like qualities of humans, and Christians will probably always disagree over the exact process used.

5) Nothing in these discoveries should pose a serious new challenge to Christian faith. It is true that the scientific evidence is overwhelmingly against young-earth creationism, but that was true before we had statistics on the similarity between humans and chimpanzees. A believer in Intelligent design would be unable to present scientific evidence proving that theory for the origin of humans, and a Christian who believed in an important role for natural selection would be unable to demonstrate that God had a hand in the way things are now, but these were true before DNA was even known to be the genetic material. It is also true that no scientific experiment has ruled out a role for God in creation, or in making or keeping things the way they are now, so an atheist, also, is on less than solid ground.

6) Can chimpanzees sin, or be converted? There is some evidence that chimpanzees have a moral sense, and understand that some things are right, and some wrong. There is no evidence in the Bible that chimpanzees, or any other animal, can sin, and be converted, except that the whole creation is said to be fallen, in Romans 8, and it needs redemption from the consequences of human sin.

Thanks for reading. Let's act more like Christ than chimpanzees do.

Note: A recent review (Perspectives on Science and Christian Faith, Sept 2009, pp. 201-203, by Darrel R. Falk, which is not yet available on-line) of More than a Theory: Revealing a Testable Model for Creation, by Hugh Ross, quotes Ross as being way off the mark on the amount of similarity between us and chimpanzees: ". . . the most complete analyses performed so far show that the similarity is closer to 85 to 90 percent." (Falk is quoting from pp. 183-4 of Ross.) Falk says that Ross, whose book was published in 2009 by Baker Books, wasn't even aware of the Chimpanzee Genome Project, which I referred to above. Ross, a prominent old-earth creationist, is, as Falk says, not a biologist. Even if Ross were right, it really wouldn't change the issues very much, if any.


i am Grateful... Kerry i am. said...

Thought provoking... all joy.

George said...

>95% of human DNA similar to chimpanzees? Hmmm... this might explain a lot of things about some people that I've been wondering about.

Great post, Dr. L.

Martin LaBar said...

Thanks for commenting, guys.

It's even closer than 95%, George, just counting the identical DNA base sequences, anyway.

h3sean said...

Cool article! I've an analogy I used with chimps and humans. I've added God in the picture too. Here's a link to my blog, hope you'd give time to read it.

Martin LaBar said...

Thanks, h3sean. I looked. An interesting post.

Anonymous said...

.... 3) There are three possible reasons for the similarity between humans and chimpanzees.

Why 3?
Actually, He/She who frames the question ....

How about there being very little similarity - only a perception of such from specific domains.

All the different sodas I give you are 99% water - one contains a drop of arsenic.... is it still a soda?

Yes - it contains mostly water just like the others.
No - it has no refreshing or life-giving value.

Martin LaBar said...

Thanks, anonymous.

I'm not sure I follow you, but, then, perhaps I was unclear myself.

"How about there being very little similarity. . ." I don't think so. There's a lot, by almost any measure.

Anonymous said...

Thanks Martin for replying.

My point was that when you phrase a question such as "How often do you beat your wife?" ... there is an automatic assumption that the basic premise (that you beat you wife) is true - which hopefully - it is not.
So my point was that your question or statement had assumed similarity between chimp and man that might not actually be there.

Thanks again for responding.

Anonymous said...

... In general, we were taught that one of the most fundamental properties of living creatures was reproduction. This seems quite reasonable. In fact a dog may be crossed with a coyote and offspring results, horses and donkeys with offspring -that may in turn be "sterile". This may prove some similarity in the species involved.
Well a German Shepherd does look like a coyote or wolf.

But when it comes to man - no such offspring with any ape has ever been substantiated in spite of rumors in Siberia may years ago.

In other words, this fundamental clue to similarity between man and any ape is obviously not there so methinks we maybe scraping the barrel.

Martin LaBar said...

Thanks, Anonymous. True, there is no credible evidence of human-chimpanzee hybrids. I hope it hasn't been tried, but it probably has.

However, there is similarity. See the Wikipedia

on the Chimpanzee genome project (which I also referred to in my fifth paragraph.) For your convenience, I quote from the article (version of October 4, 2010):
"Typical human and chimp homologs of proteins differ in only an average of two amino acids. About 30 percent of all human proteins are identical in sequence to the corresponding chimp protein."

This is remarkable similarity.

Thanks again.

Anonymous said...

Fair enough, thought we could hop on this one too. From
Tuesday, 18 November 2008
"Australia's kangaroos are genetically similar to humans and may have first evolved in China, Australian researchers have said.

Scientists said they had for the first time mapped the genetic code of the Australian marsupials and found much of it was similar to the genome for humans, the government-backed Centre of Excellence for Kangaroo Genomics said.

'There are a few differences, we have a few more of this, a few less of that, but they are the same genes and a lot of them are in the same order,' centre Director Jenny Graves told reporters in Melbourne.

Anonymous said...

OK, let's fast forward from 2008 to ScienceDaily (May 30, 2009)

(here again is what I meant by he who frames the question... it's as if only one general answer is admitted, so is an agenda being put forward comes to mind?)

Actually, we may not have anywhere close to all the facts on this subject, for example do you ever use the word "Junk" DNA? or heard it used?, turns out it's not Junk at all...)

..ScienceDaily (May 30, 2009)..

Saved By Junk DNA: Vital Role In The Evolution Of Human Genome

"Most people do not realize that all our genes only comprise about 3% of the total human genome. The rest is basically one large black box," says Kevin Verstrepen, heading the research team. "Why do we have this DNA, what is it doing?"
Researchers at K.U. Leuven and Harvard University show that stretches of DNA previously believed to be useless 'junk' DNA play a vital role in the evolution of our genome.

They found that unstable pieces of junk DNA help tuning gene activity and enable organisms to quickly adapt to changes in their environments . ..

Anonymous said...

Now, is your 95% or 97% similarity 97% times 3% (of the human genome) or is it more, based on current knowledge?

my worksheet:
0.97 x 0.3 = about 2.9%

Hmm.. might explain some obvious differences between humans and chimps unless they're making right royal monkeys out of us.

Anonymous said...

"This finding revealed a surprisingly important role for piRNAs, as well as junk DNA, in stem cell division," Lin said. "It calls upon biologists to look for answers beyond the one percent of the genome with protein coding capacity to the vast land of junk DNA, which constitutes 99 percent of the genome."

Reference: Nature: Advance Online Publication doi:10.1038/nature06263

This research was supported by the Mather's Foundation and the National Institutes of Health.

Anonymous said...


* The genomes of more than 180 organisms have been sequenced since 1995
* The genomes of mice and rats are 88 per cent similar to that of humans and have versions of nearly every human gene, hence the animals’ extensive use in medical research
* The dog genome is also 75 per cent similar to that of humans. One of the dogs sequenced in the dog genome project was a poodle named Shadow. Shadow belongs to Craig Venter, whose own genome was sequenced during the human genome project
* The pufferfish genome was sequenced in 2004. It shares many genes with humans, but is eight times smaller. During the course of the pufferfish genome project 961 new human genes were discovered
* Other organisms whose genomes have been sequenced are the chicken, sequenced in 2004, with a 60 per cent similarity to that of humans, the fruit fly (50 per cent) and the daffodil (35 per cent)

Martin LaBar said...

Thanks for all the information, Anonymous.

The reference for the material in your last comment appears to be here.

It summarizes the main point pretty well, namely that the genes of organisms are strong evidence for descent from a common ancestor. I presented alternative explanations in my original post.

As to so-called junk DNA, it is my understanding that genome sequencing projects have included such DNA.