Do "Missing Links" Prove Evolution?

Post Author: Bill Pratt

Seldom a month goes by that a major announcement isn’t made about a fossil that demonstrates the evolutionary lineage of some animal.  These announcements have always fascinated me because of the bold claims that are made.

But something I have struggled with for a long time is understanding exactly how paleontologists can make decisive claims about lineage based on the fossil record.  Recently, Greg Koukl, of Stand To Reason, wrote a fascinating article about this very topic.  In particular, he was addressing the fossil dubbed “Ida,” which is supposedly a missing link in the human evolutionary chain.  According to one scientist, “Ida is an example of a transitional fossil between primitive primates and the prosimian and anthropoid branches, the latter of which eventually led to humans. . . . She is the earliest, and one of the most significant links, ever found.”

Koukl explains the way paleontologists label a fossil a “missing link”:

If a fossil is midway in development between two other specimens (if it shares physical characteristics of both) and falls between them in time, it is considered transitional even if the distances in time are very great. This is the empirical situation paleontologists actually face when surveying the fossil record.

Since Ida existed 47 million years ago, and modern humans were found in the fossil record 100,000 years ago, there is a huge time delta between the two.  Paleontologists need to fill in the blanks between the two fossils of 46.9 million years.  There are, indeed, a handful of hominid fossils before modern humans, such as the well-known Lucy, which is one of the earliest hominid fossils ever found.  Lucy existed 3 million years, but that still leaves a 44 million year gap to Ida.

According to Koukl, “Simply because Ida’s bodily characteristics (morphology) rest between two groups on the Darwinian tree of life, she is immediately declared the common ancestor – the missing link – between both groups,” regardless of the massive amount of time separating them.

Koukl asks the reader to imagine the Darwinian tree of life as a series of roads and highways leading from east to west in the continental US.  If you have access to Google Earth, you could see the highways all interconnected from satellite photos.  But sometimes there are clouds that block your view and you cannot see all the roads as they are interconnected.  Imagine further:

A massive front covers the continental U.S. save for occasional gaps that allow you to glimpse short pieces of highway every few hundred miles.  Your task is to determine which sections of road connect with each other to form routes from the east to specific destinations in the west like L.A., San Francisco, or Seattle.

Would you be justified in inferring a connection if one section in west Texas fell between a length of highway in central New Mexico and one in southern Arkansas as long as each section ran roughly in the same direction?

I think you can immediately see the peril of this approach.  Clearly, there would be no way to tell from the empirical evidence alone which sections of road connected with other segments of highway to lead you to a specific destination. In the same way, how can we have confidence that one specimen in the fossil record is the ancestor of another specimen that is millions of years removed from it in time?

The lesson here is simple: You must first know that the highways link up before you can trust that any particular segments of the roadway connect the route. By parallel, you must first assume that evolution is true before you can place alleged transitions in their “proper” evolutionary pathways.

In other words, missing links can never answer the question as to whether common descent has really occurred.  Only after you assume that common descent is true does it make sense to try and make these ancestral connections between fossils.  The fossil record cannot prove that humans are descended from a creature that lived 47 million years ago.

If all the clouds cleared away, and we could see the millions of small transitions that occurred between Ida and Lucy, and then Lucy to modern humans, then we would have a compelling case for claiming that we know the ancestry of humans.  But the fossil record is fragmentary, leaving gaps of millions of years between fossils, which represents millions of transitional forms.

As long as large clouds block our view  (i.e., the fossil record is fragmentary), we cannot know, and it is extremely disingenuous of scientists to tell us that they do know these things.  The data does not allow for that kind of confidence.

  • World of Science

    If evolution is true and humanity is the pinnacle of the evolutionary process, why does a process as basic as human reproduction fly in the face of everything that evolution holds true? Does it?

  • e-dogg

    You said:
    “… it is extremely disingenuous of scientists to tell us that they do know these things. The data does not allow for that kind of confidence.”

    It is even MORE disingenuous of you to misrepresent a large portion of the scientific community. First and foremost, Ida has been SUGGESTED as a POSSIBLE transitional fossil. No one has claimed certainty in this matter, and there is still quite a bit of discussion among scientists on Ida’s place in the ancestral tree. To claim that scientists are presenting this fossil as a definite common ancestor is not only absurd, but also bearing false witness.

    Next, to take this one example of a cloudy area of the fossil record and apply it to the entirety of paleontological research displays either a total lack of familiarity of the subject or wanton disregard for the truth. There are parts of the fossil record that give us very good resolution of the species transitions over a particular time period.

    To expand on your analogy, when looking at the satellite imagery you can see large areas of roads completely unobscured, and they unquestionably are interconnected. Then there are some areas that are only partially osbscured. But you can see roads on either side of the clouds, and based on your experience with the areas you can see entirely, you have every reason to expect the roads are connected in some way. You can even apply what you’ve already seen to make educated guesses about connections between divided highways, gravel roads, city streets, etc. You may not get all the details exactly right when drawing your map, but you’ll certainly do better than if you just assumed all roads are dead ends until you see ALL the intersections.

    Now, where there are large areas that can’t be seen, you’ll be doing a lot of guesswork on the connections, but that’s OK, because you won’t be claiming this part of the map has great certainty. Someone will probably come along later with a different satellite image and maybe correct, refine, and fill in missing detail.

    I’d also like to point out that evolutionary relationships aren’t based entirely on the fossil record. There are many lines of evidence, such as biogeography, phylogeny, and genetic analysis (check out endogenous retroviruses for one of my favorites) that support the accepted conclusion of life’s shared common ancestry. To deny this conclusion, you’ll have to ask yourself why god would create all these roads that look like they are connected, but for some reason he put little roadblocks across every intersection.

  • Bill Pratt

    “There are parts of the fossil record that give us very good resolution of the species transitions over a particular time period.”

    The only way we can see a full map is if we have a continuous chain of fossils over the 500 million years since the Cambrian explosion (this is when most of the major phyla are first found in the fossil record). This would require enormous numbers of fossils, and we just don’t have them, and we will never have them because most dead animals don’t leave fossils behind.

    We have a one-mile patch of road here and an offramp exit there along the thousands of miles of interstates and highways going from the east coast to the west. We have, in effect, a big “connect the dot” game where paleontologists estimate how the dots should be connected. There is no way of knowing that two dots are connected because we are dealing with a historical science that predates human observers. We can make good guesses, but we cannot know with a high degree of certainty.

    I understand that the fossil record does provide some interesting data and that it can be used to support the theory of common ancestry, but when scientists claim that they have found “missing links” they are no longer doing science. They are sensationalistic and misleading.

  • Jason

    The road analogy is poor because it seems to suggest that any two pathways could possibly connect were the clouds to be removed, that is to say that any species at one point in time could be related to any other species further down the line. This is an fundamental misrepresentation of evolutionary theory and is somewhat sensationalistic and misleading in its own rite because no one who argues on behalf of evolution would claim that that is true.
    Now, if people are claiming Ida as a possible ancestor then its because of a similarly structured morphology. While we cannot, with certainty, say that we evolved from that species (because it may have been an offshoot of an earlier species and that it eventually became extinct) we can say that humans and that species share a common ancestor simply because it is reasonable to assume that we:

    A. have ancestors
    B. developed from an earlier species with similar characteristics as our own

    What we as Christians cannot afford to do is engage in conversations about “good” and “bad” science if we are not willing to recognize science when it IS good or stop each other from presenting science which is bad. If we are going to enter the conversation at all it needs to be as educated participants. While the spirit of debate should be encouraged since it’s the dynamic nature of science to respond to reasonable objections and substantiated alternatives, the veil of willful obstinacy will need to be removed first.
    If we can’t do this much then Christianity has no right but for its numbers to be involved in any conversation than one of faith.

    I love the blog, I hope I didn’t come across as disrespectful. I appreciate both the thought and insight from Bill and “e-dogg.”

    Further, a clarification for “World of Science”:
    Terms like “pinnacle” would come from the belief that we are the most “evolutionarily advanced” species when really, according to evolutionary theory, there is no such thing. Evolution regards every species currently living as occupying the same place in the evolutionary ‘hierarchy’. “Pinnacle” would suggest that a roach is “less evolved” than a chimp simply based on the complexity of each organism. However, a roach can live in a wider variety of climates and in greater numbers too. And using the quotation by Antoine de Saint-Exupery “Perfection is achieved perfection not when there is nothing left to add, but when there is nothing left to take away” we could argue that the roach is of a higher order. Neither of these are true because both rely on the interpreter to assign some value to different attributes when evolution only suggests that each species adapts to its environment over time. If a species exists today its because sexual selection selected for traits which would lead to its survival in its environment and so on and so on. Now, conscious thought and language are unique to only humans and Bill has posted an article on this before which I think it appropriate:

  • Bill Pratt

    Hi Jason,
    I’m not sure I understand your objection to the road analogy. Could you explain it in a different way?

  • Jason

    Certainly! I apologize. Basically, the road analogy acknowledges that there are relationships between species and that because there is a lack of resolution for large periods of time we can’t assume two are directly connected. And that is partially true because we cannot state definitively that Ida is a “missing-link” because as I said previously, Ida may have evolved from a common ancestor and died out without producing any presently living ancestry. But in all likelihood it is more closely related to that common ancestor than other fossils we have and thus the term “missing-link,” while semantically and technically might not be 100% correct it can be assumed to be so close as to make no real difference. Where the road analogy is weak is that it dismisses our relation to Ida at all when we can state fairly definitively that we (both humans and Ida) developed for much of our history along the same evolutionary path because we carry an overwhelming amount of similar characteristics.
    Before I begin, I’m not trying to make this seem childish (honestly) but this is how I would have to rewrite the road analogy (in my head) for it to actually be more accurate to evolutionary theory. Roads through the clouds all look the same while species over time look like their ancestors. If we wanted to more accurately apply the road analogy we could say that there is a single road or let’s say a collection of three roads all starting on the west coast and they look somewhat similar (meaning that we can tell that they’re roads), one may have four lanes and yellow painted lines, another may have two lanes and white lines and another may be made of gravel. Now, there may be clouds for a while, but when they clear the roads don’t all look alike, nor do they look exactly like the ones that began on the west coast. Rather there is now a five lane road with yellow painted lines, two gravel roads, one with gray pebbles, one with finer brown dirt. And there are half a dozen two lane roads with varying line colors. Each time you move further east you’ll probably see more and more roads with varying characteristics. By the time you get to the east coast you have a lot more roads and many have a lot more distinguishing features (traffic lights, signs, billboards, on ramps, etc.) While it is impossible to definitively state any one road leads to another road without full clarity we can make educated guesses with a fair degree of certainty that the gravel roads at the first cloud clearing junction are likely connected to the original west coast gravel road rather than any of the other roads. And that on the east coast the three lane road with white lines with traffic lights and on and off ramps is probably related to the three lane road at the previous cloud clearing with the white lines and on and off ramps but with no traffic lights. While the two might not connect directly, if you could follow both roads back west they will connect at some point earlier merely because they carry a number of similarities and it’s doubtful one of the gravel roads turned into a three lane road paved road with traffic lights, etc. over the course of one cloud cover. These are reasonable assumptions. And I think that is all the people who discovered Ida are trying to say, though the import of the discovery is probably exaggerated somewhat for the benefit of their funding. Ha ha ha!

  • Bill Pratt

    Thanks for the clarification. I see your point better, but I don’t think you’re dealing with the thrust of the blog post, however. Let me try and state the point as succinctly as I can.

    You must assume that fossils with similar characteristics that are separated by millions of years are related to each other by direct genetic ancestry in order to assign a particular fossil as a missing link. In other words, you must first assume there exists a chain before you can find its links.

    But the very question that people are asking is this: Is there really a chain at all? In your response to me, you just assume that the chain exists because of an “overwhelming amount of similar characteristics” among fossils. But there are other possible explanations of why fossils separated by millions of years may have common characteristics.

    In addition, scientists routinely exaggerate their claims in order to gain attention and funding, as you joked. When you announce to the world that you have found a missing link, the clear implication is that you have found a link in a single, continuous chain.

    You are allowing for all sorts of sloppiness in scientific reporting when you admit that there may exist many chains laid side by side and the “missing link” fossil is a link in chain #654 and modern humans are actually to be found on chain #789. You may have to literally jump chains to make the link. This is fundamentally misleading and scientists should just be honest and say something like, “We found this fossil which has some common characteristics to these other fossils that existed millions of years later. They may or may not be related in an evolutionary chain. We’re not sure and we may never be.”

  • Jason

    I gotcha and I think you’re right and people are justified in questioning the existence of a ‘chain.’ I did. I just did some research and came to a conclusion which favors an evolutionary explanation but many do the research and reach differing conclusions. And you’re right to say that fossil records are incomplete and that they can’t prove evolution, but they can support it, and there’s a wealth of other information as your first commenter stated (“biogeography, phylogeny, and genetic analysis”) that also supports it. And when it’s all put together (I, personally, think) we can look at it and say “Sure, there is missing information, but we have a pretty good idea of how this works.”

    Just as when we’re confronted by skeptics who seek to pick apart the Bible by citing Leviticus 19:19 or, as you mentioned in your most recent post, Mark 2:26 or other obscure verses as reasons why the Bible is irrelevant, out of touch or has errors we must respond by saying “You can only truly make an informed decision when you arrive having not already made one and are willing to view the whole.”

    Bill, honestly, thank you for responding! Keep up the good work!

  • Bill Pratt

    Thanks for your response, Jason. I have looked at a lot of evidence for the traditional Darwinian view and I have serious scientific problems with the mechanisms of natural selection and random mutation accounting for the diversity of life. Michael Behe’s Darwin’s Black Box, along with several other books in the same vein, pretty much convinced me that the theory cannot explain very much of evolutionary history.

    With regard to the theory of common descent, I remain undecided. I believe that the scientific evidence is certainly stronger for at least some common ancestry, although I am deeply skeptical that any kind of case can be made for all life evolving from a single primitive organism. I think, at a minimum, life had to have “evolved” from numerous starting points. I am also very troubled by the Cambrian explosion and don’t see how common ancestry can really deal with this fact of the fossil record.

    I continue to research the issue and try to keep an open mind about it.

    Thanks again for your time,

  • Bill Pratt

    And right on queue, here is the latest on Ida.

  • Jason

    Ah, but that is science’s greatest strength, that it’s dynamic. They redirect under new, more complete evidence. Unchangeable ideology is not science, nor should it be.

    In the end it looks like it mostly served to net the History Channel some corporate ad dollars – and the search marches on besides.

    Thanks for the update!

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