Debates Within Evolution

Given that Evolution is now accepted as fact by most of those who have been exposed to it (leniency, please)…What great debates are currently going on within the field of
Evolution? Are there any issues/processes/etc for which two or more sides are sharply divided?

memetics is a pretty controversial idea directly stemming from evolution theory.

As far as I know, evolutionists are pretty sketchy in regards to details on how consciousness really came to be.

Finally I haven’t seen any strong theories (big bang is a work in progress) as to the cosmological argument.

Calling Darwin’s Finch… where are you? :slight_smile:

There’s a big and as yet (apparently) unresolved debate regarding the timescale that mutations occur, with the two opposing camps headed by (the now deceased) Stephen Jay Gould, versus Richard “everybody else is stupid except me” Dawkins.

Gould argued that the proces of evolution would occur dramatically fast (in geological terms, at least), where fairly rapid changes in the local environment would allow the rapid emergence of newer species within the limitations imposed.

Dawkins, on the other hand, argued that evolution itself was a process that could only take place over long periods and in general disregard to any rapid environmental processes.

Personally, though, Dawkins usually sounds like an utter jerk - he is to science what Benny Hinn is to Liberal Christians.

The concept of “meme” is not biological in nature, and as such is not part of any real debate within evolutionary biology. Likewise for cosmology.

The debate about mechanisms which differentiate macro-evolution from micro-evolution (if any) is still ongoing. Also, the locus of selection (gene, individual, etc.) appears to be contested. And, of course, a universal concensus on the definition of “species” is still forthcoming.

Actually, a summary of a few current discussions can be found from this review of Conceptual Issues in Evolutionary Biology.

What nonsense you speak Mr. Finch. The meme by its very nature is entirely biological. That is unless you hold the hypothesis that our thoughts come from immaterial astral planes?

Nonsense in return. A meme is analogous to a gene in concept only: like genes, memes can be passed on to future generations, undergo a form of selection, etc. A meme is itself nothing more than a conceptualization, useful for helping to understand how certain cultural / sociological phenomena spread or persist from generation to generation. None of which makes the concept of “meme” the least bit biological in nature.

Our capacity and mechanism for thought is biological, and therfore a product of our evolutionary history. Our individual thoughts, however, are not rooted in our evolution.

Are you talking about speciation, not mutation? If I read you correctly, you seem to be referring to Punctuated Equilibrium vs Gradualism.

Most evolutionists accept that these two are not mutually exclusive.

In an Antropology survey course a few years back I was introduced to a evolutionary debate that stuck with me. It had to do with human evolution, and the spread of mankind across the globe. The one theory was that successive waves of Homo _________ evolved in Africa and then set out into Europe and Asia, outcompeting and then replacing the previousspecies who had already migrated. The counter to this was the idea that some early ancestor had migrated across Eurasia, and then (insert hint of personal disbelief here) simultaniously evolved into the next species without contact with other populations. In other words, if three seperate populations of Homo habilis existed, one migrating to France, on the Sumatra, and one staying in East Africa, all three would evolve into Homo erectus without contact with one another, despite variations in environmental pressures. I didn’t buy it, but since it was 1st year Anthre, the instructors were more focused on having us memorize facts than encouraging debate.

Urbna, apologies - I’ve been a long time out of biology so I tend to confuse the terms perhaps too easily.

As for the exclusivism - so far as I know the conflict between Dawkins and Gould was precisely that.

AFAIK, these two mechanisms are not mutually exclusive. PE takes over during periods of great stress, while gradualism holds sway when the environment is relatively stable.

PE isn’t a separate process that “takes over” at any time - it’s an explanation for the appearance of the fossil record. Specifically, the “gaps” present in the fossil record are not entirely due to the poor likelihood of fossilzation, but have a lot to do with how speciation works. By and large, speciation is the result of diverging populations, rather than the slow, steady transformation of populations. As such, we should expect to see species appear rather suddenly (the speciation event, which in terms of geological time, happens very quickly), punctuated by periods of apparent stasis (wherein a species may undergo gradual transformation, without much divergence). Once a population reaches a certain size, it will stabilize - i.e., reach equilibrium.

The speciation event itself does not require a period of stress, it only requires (and there is debate as to whether separation is an absolute requirement: see “sympatric speciation”) that a segment of a population be separated from the main group. Those two populations will then begin to diverge from one another, eventually becoming separate species.

mcbiggins, the competing theories you are describing are the “Out Of Africa” theory (speciation occurred in Africa and the world was populated by successive waves emanating from Africa) and the “Mutilregionalism” theory (holding that some pre-sapiens ancestor left Africa, then continued to evolve in multiple locations, but apparently did not reach the point where interbreeding was impossible before the separate species began running into each other and interbreeding). (One point to remember for Multiregionalism is that while one definition of species is “not producing fertile offspring,” that definition is a handy expression that is not an absolute in the opinion of many biologists.)

The “Out of Africa” theory has been steadily beating down Multiregionalism on points over the last few years. I doubt that all the Multiregionalists have given up, but they are becoming fewer in the face of the current understanding of the discovered facts.

Yes, the multiregionalists are very much in the minority. Their most vocal adherent is Milford Walpoff (sp?). Ironically, he’s kind of a walking edvertisement for his theory as he looks a lot like a Neanderthal.


The species you are thinking of is H. erectus migrating out of Africa and turning into sapiens in various parts of the globe. There is some slim evidence that habilis migrated out of Africa, but the std theory is that it was erectus.

Also, I’m surprised no one has mentioned the 2 dinosaur controversies:

  1. Were some (like T. rex) warm blooded?

  2. Did birds evolve from dinos?

These are still pretty hottly debated, and #2 is getting interesting as it appears that a whole bunch of dinos had feathers. I think the latests issue of Sci Am has a good article on that.

I can say that I didn’t bring those up for a couple reasons:

  1. They do not address evolutionary mechanisms. The only debate would be at what point in the reptile -> bird lineage did “warm-bloodedness” evolve, or where birds and dinosaurs lie within the reptilian evolutionary tree. The latter is more an example of a phylogenetic debate than an evolutionary one.

  2. They really aren’t that hotly debated anymore. The evidence points very strongly to a) dinosaurs being warm-blooded (or, at the very least, intermediate between ectothermy and true endothermy, and it is likely that individual lineages varied in their degree of endothermy) and b), birds evolved from theropod dinosaurs. Such may have been hot topics for debate 20 years ago, but now you would find very few paleontologists who would disagree with the aforementioned points.

Note that there may well be a number of ongoing debates regarding this phylogeny or the origin of that structure or characteristic, but those arguments tend to exist because of incomplete data rather than a disagreement with any fundamental mechanism of evolution. This is why the aforementioned “dinos-to-birds” debate has died down quite a bit of late: we’ve discovered a great deal more fossil evidence which sheds light on what was going on during the transitional period, so we have alot more data to work with than we did 20 years ago. We still may not be absolutely certain when the transition occurred (with each new find seemingly vying for the position of “first bird”), but there is little doubt that it did.

Okay, what specific molecule is a meme on? Could I at least have a generalized formula for the subunits?


I realize we’re nitpicking here, but wouldn’t you say that the dino/bird debate is about as “hot” as the Out of Africa/Multiregional debate? I know you didn’t throw the latter out here as an “issue”, but I seem to hear at least as much chatter about the dino/bird issue as I do about the OoA/M issue.

I think that the origins of humans are a lot “hotter” than, say, bird origins. For one thing, I think many people get a lot more emotional, if you will, when discussing, well, us. For another, I think the evidence as to exactly how we came to be human is still elusive - yet, that doesn’t seem to stop many anthropologists from coming up with “pet” theories, based on little evidence and a lot of speculation, and defending them passionately.

For birds, I think much of the debate surrounds the form of the tree, rather than where it came from. Granted, there are a few hold-outs who either feel that birds came from a different archosaurian ancestor (that is, they are archosaurs, but not dinosaurs), or came from a different group of reptiles altogether. But those represent a definite minority, based on the literature I’ve seen.
Anyway, as I mentioned, much of the debate surrounding bird origins now seems to center around “who was really first?” Archaeopteryx has thus far taken on all comers and remains the “first bird”, but there are still challengers out there. And with the numerous new fossils coming out of China, the issue of bird phylogeny isn’t likely to be settled any time soon. However, ultimately it is accepted, almost as a given, that birds evolved from a maniraptoran (the group which also includes Deinonychus and Velociraptor) ancestor, and that the bird “root” lies therein, regardless which form eventually comes in “first”. The recent discovery of Microraptor (the “four-winged dinosaur”) merely raises the possibility that birds evolved sooner than expected, but Microraptor itself is thought to be a dromaeosaur (based on tentative analyses). Note also that there is still a significant debate about how, exactly, flight evolved within birds, as well as how feathers themselves (which now appear to have been present well before birds proper) evolved.

So, there is a debate, certainly, but I think the focus of the debate is somewhat different, tending to center around phylogenetics than evolutionary mechanisms. I chose not to include such debates (and, really, there are many of these sorts of debates within evolutionary science and related fields) in my original post largely because the focus is not so much “by what mechanism” as “by what path”.

Most of the debate in my field is technical (the large points are all pretty nailed down). Things like “Is there evidence for stabilizing selection on the 5’ cis-regulatory elements of the pair-rule gene even-skipped.” Or stuff like that.

But, more generally, I think the role of standard morphology based phylogeny in relation to molecular phylogeny is a pretty wide area of debate.