I don’t like to talk much about Creationism, but here I go again. I want to expand on a point I made in an earlier post: Darwin should have called his book On the Illusion of Species. I’ve tried to get rid of technical terms and keep this readable. The point I’m working up to is that when a creationist says “animals only reproduce within their own kind”, they are right—if they use some technical language.
The first thing I want to do is to pull “abiogenesis” away from “evolution”. These are distinctly different theories, and they are theories in completely different ways. Whereas evolution is a scientifically validated and evidentially substantiated theory, abiogenesis is the title to a group of hypotheses. You can claim that God is responsible for abiogenesis (and evolution, if you want). But abiogenesis deals with the move from non-life to life. Evolution is about diversifying life after it appears.
I haven’t come across a model of abiogenesis that claims there was a rock on Tuesday that was life on Wednesday. Abiogenesis is a process, not an event. The most likely order of this process is this: inorganic chemicals, organic chemicals, expanding organic chemicals, expanding and dividing organic chemicals (this is a type of imprecise copying), to ever-increasing levels of precise copying. Because there is a stage of imprecise copying we could see any one litre of organic chemicals giving rise to many distinct precisely replicating chemicals. These precisely replicating chemicals are the precursors to DNA. DNA controls its own chemical environment, which is what you are: the chemical environment of your DNA. Over time evolution has built you to encourage DNA to copy itself.
After abiogenesis evolution can start. This makes life diversify. Life can diversify faster if its copying mechanism is less precise, and life can specialise if its copying mechanism is more precise. In my earlier post I said that if we had a perfect-resolution fossil record between a modern animal and its historic ancestor then we would not be able to make any meaningful distinctions between the two; they are essentially that same animal. The same is true of two modern animals and their common ancestor: if we had a perfect-resolution fossil record then we shouldn’t be able to meaningfully find the split (the “speciation event”).
But from a modern perspective, the speciation event clearly happened: the two animals cannot interbreed and are different species.
The taxonomic classification of life is a good example of this. Taxonomists label life according to ever-more specific group-names. In ascending order of precision, these group names are as follows: Kingdom, Phylum, Class, Order, Family, genus, and species. The common ancestor of an elephant and an earthworm would still be an animal (Kingdom: Animalia); the common ancestor of a carp and a giraffe would still be a vertebrate (Phylum: Chordata); the common ancestor between an orangutan and a human would still be a primate (Order: primate); and the common ancestor between gorillas and chimps would still have been an African ape (this is actually a subclass within the “Order” class, there are a lot of subclasses to consider). Evolution gives us diversity within a set, or a class.
So abiogenesis gave us our first set: life. Diversification within that set has given us plants and animals and fungus and bacteria; these are the “Kingdom” sets. Then evolution only works within those sets; no animal will evolve into a plant. Within the animal kingdom evolution has given us vertebrates* (Phylum: Chordata) and non-vertebrate sets (like mollusca which includes octopi, and Arthropoda which includes insects, spiders and crustaceans). No vertebrate would evolve into a non-vertebrate species.
*technically we define chordates by their spinal cord (the nerve) and not the spinal column (the bones). But I think the slight inaccuracy makes the point clearer.
So when a Creationist says that animals don’t evolve into another “kind”, they are correct. Evolution causes diversity and specialism within a broader set. Canines will always give canines, primates will always give primates, vertebrates will always give vertebrates, plants will always give plants, life gives life. Always the same kind.
Work by Dr Jack Szostak (here is a Youtube video summary)
The Blind Watchmaker by Richard Dawkins (although, this focuses more on the Cairns-Smith inorganic self-replicating clays)
Wikipedia (and then follow the references)
The Youtuber AronRa’s series “Foundational Falsehoods of Creationism“
Secondary school text books (I know it’s in there, I was taught it and I have taught it).
For a contrary view:
Reason for Hope’s series on evolution (here is part 2, but it’s all worth a read).
What ever this is. (The other link is more intelligent that this one, but this is what you come up against.)