Do traceable lines of descent exist that might ultimately permit characterization of the genomes of organisms basal to the clades for the highest categories? The answer to this question increasingly appears to be no. Recent work on genomic structures demonstrate that all living organisms are genetic composites: mosaics and chimeras composed of bits and pieces of multiple genomes derived from multiple sources.
The base of the universal tree of life appears not to have been a single root, but was instead a network of inextricably intertwined branches deriving from many, perhaps 100 or more, genetic sources. The traditional version of the theory of common descent apparently does not apply to kingdoms as presently recognized. It probably does not apply to many, if not all, phyla, and possibly also not to many classes within the phyla. (from Malcom Gordon’s paper on monophyly)
When Intelligent Design advocates talk to evolutionists concerning the origin-of-life, the standard response is almost always something like “Evolutionary theory says nothing about the origin of life. Whether it was RNA world, or a special act of creation, evolution is an entirely different subject than abiogenesis.” However, I think that this argument is illegitimate. In fact, large-scale evolutionary theory depends thoroughly on specific notions of abiogenesis.
If someone wants to see the Darwinist position on this question, see the following articles by Darwinists:
First of all, clarifying definitions. By “evolutionary theory” I am referring to neo-Darwinism — the combination of RM+NS (or any other non-telic evolution) and Universal Common Ancestry. The dogmatism on these issues admits to a dependence on a specific, narrow view of abiogenesis.
Let’s first start out exploring a question. Did the organisms in the Cambrian explosion evolve from creatures dissimilar from themselves? Or, more specifically, did all (or at least most) of the organisms in the cambrian explosion share a common ancestor?
The traditional evolutionary answer is “yes”, though the specific characterizations of what that ancestor looked like I assume is in quite a bit of debate. So, the next question is, “How do you know?” There are several possible answers:
- There are organisms in lower strata than the Cambrian organisms.
- Since everything descended from a single (or a pool of) single-celled organisms, they would have shared an ancestor in that pool.
#1 is easily done away with. My grandparent’s dog is also in a lower strata than I will be some day, but that does not indicate ancestry. #2 is where I would like to focus my arguments.
- If you do not rely on a specific conception of abiogenesis, how do you know that life only arose once, or in one pool of organisms?
- If you do not rely on a specific conception of abiogenesis, how do you know that a multicellular organisms must have had a single-celled organism as an ancestor?
- If you do not rely on a specific conception of abiogenesis, how do you know that a fossil sequence of high disparity is not the result of multiple abiogenesis events separated in time, rather than representing an ancestral lineage?
Even assuming a fully naturalistic abiogenesis, the above questions cannot be adequately answered unless a specific conception of abiogenesis is used as the basis. Malcom Gordon’s paper mentioned above details this issue from an entirely naturalistic perspective, comparing an abiogenesis scenario where life arose multiple times according to multiple paradigms versus the standard neo-Darwinian conception of life arising once. He even placed the root of where “common ancestry” was the norm (as opposed to lateral gene transfer in the specific scenario he was thinking of) fairly far down the taxonomic scale.
In addition, if you remove the requirement of naturalism in abiogenesis, then there is absolutely no reason at all to suppose either common ancestry or descent from unicellular creatures. This doesn’t mean that it is false (in fact, many in the ID movement agree with common ancestry). The point is that common descent is based on assumptions about abiogenesis, not from evidence alone.
But even more importantly, it no longer constrains you to RM+NS as a change mechanism. If your view of abiogenesis involves intelligent agency in any way then there is absolutely no reason whatsoever to hold on to RM+NS as the primary change vehicle in organisms. The experimental evidence is pointing to structure and order in the way that genomes change. If you don’t hold that life is an accident, then why would you hold that the mechanisms of change are accidental as well, especially in the face of all of the mounting evidence to the contrary?
So, without a specific concept of abiogenesis, there is no reason to assume that life arose once, or that organisms needed to use RM+NS to produce the higher taxonomic categories. Without a specific concept of abiogenesis, there is no reason to assume that life arose simply and then became more complex later. Abiogenesis is inextricably linked with the large-scale views of evolutionary theory.
So, the question is, why is it that Darwinists are so adamant about the separation between abiogenesis and evolution? There are a number of reasons I have thought of, but I don’t think they are exhaustive. I’m curious to hear yours. The ones I have thought of include:
- Common worldview — the set of assumptions that lead to thinking that Darwinism is true might be the same set of assumptions that lead to thinking of the Darwinian view of abiogenesis. Thus, you keep it as a “working conception”. The idea that they are “unlinked” stems from the fact that, from Darwinian assumptions, the constraints of abiogenesis mean that it must fall within the Darwinian concept, even if the details are sketchy. The idea that other forms of origin-of-life might affect all of this never enters the thinking on the basis that people who believe those things are nutty and only need to be placated (“oh yes, evolution does not rule out that God was the originator of life — now move along and don’t ask any questions about the nature of that origin or how it might affect the rest of evolution”), not treated rationally.
- Embarrassment — it could be that many Darwinists know that studies of abiogenesis have been woeful at best. Despite the fact that Darwinism is rooted on assumptions that include abiogenesis, they are worried that the failure of abiogenesis studies will reflect poorly on evolutionary theory. Therefore, the disconnecting of abiogenesis with Darwinism is a means of life-preservation — to simply cut off from discussion the more abysmal findings about the theory. Of course the problems with abiogenesis are basically the same as with RM+NS evolution — how does information arise on its own? It’s just a more pronounced problem with abiogenesis and not as easy to wish away.
- Tradition — the notions of universal common ancestry, RM+NS, and abiogenesis are so thoroughly embedded in evolutionary tradition, that practitioners have difficulty separating out the “received wisdom” from the empirical data. Therefore, even though they know that evolutionary theory _should_ be separate from abiogenesis, they have too much institutional baggage to deal with the issue on a broad scale, and noting the implications it could have across the board. Those who attempt to do so in one area are shot down by others more entrenched in evolutionary tradition.
(if you think of others, please post them in the comments)
The biggest problem I have is not as much with Darwinists having this concept of abiogenesis or with them basing their theory on it. All ID-based theories likewise have their own conceptions of the origin-of-life that their theories come from, some of which include common ancestry. The problem is the deceptive tactics of pretending that their theory is separable from abiogenesis. That is simply not intellectually honest.