In the face of the claim that all forms of life were recently divinely created in something much like their current form, there is abundant evidence of new species forming right now, all around us.
The definition of the term ‘species’ is a relatively complex, and somewhat contested, matter in biology. A quick rule of thumb is that members of different species can’t reproduce sexually with one another in a sustainable way. It’s probably not a full and accurate definition, but it works for most cases.
That last distinction, about sustainability, addresses situations like mules: the offspring of a horse and a donkey, which are different species, is bred by humans for our purposes but is itself barren and unable to reproduce. If humans stopped breeding mules, they’d die out in a generation (I guess aside from random liaisons between wild horses and donkeys).
We see new species of plants, birds, insects, fish, amphibians and other species with relatively short lifespans arise regularly: I won’t link here, but just google ‘observed speciation’ for plenty of examples.
(If I were a real biologist I’d spend more time on all the layers of kingdoms and genera and phyla and families and such, but I’m not, so I won’t: there are very good Wikipedia guides if you’re interested.)
The common creationist response is the one that was parodied with ‘crocoduck’ memes: “We have never seen a fish turn into a cat: the new species you talk about look exactly like the thing they evolved from”. This is related to the claim that there are no ‘intermediate species’ in the fossil record: what they are looking for is something that is very obviously partly one recognisable modern species and partly another.
When faced with evidence of the ways in which species adapt to their environment – including things like the development of antibiotic-resistant bacteria – the creationist response is often “Well yes, God designed in adaptability to help life survive, but that’s only micro-evolution within species. Macro-evolution that creates new species (that are visibly and noticeably different) doesn’t and can’t happen.”
One of the quasi-scriptural notions used to support this distinction between micro- and macro-evolution is ‘baramin’. It’s not a real Hebrew word, it’s a recently-coined (well, 1941) term that (ungrammatically) combines the Hebrew words ‘bara’ (created) and ‘min’ (kind).
The scriptural creation account includes these phrases:
Genesis 1: 11-12, 20-21, 24-25 (King James version)
11 Then God said, “Let the land produce vegetation: seed-bearing plants and trees on the land that bear fruit with seed in it, according to their various kinds.” And it was so. 12 The land produced vegetation: plants bearing seed according to their kinds and trees bearing fruit with seed in it according to their kinds. And God saw that it was good.
20 And God said, “Let the water teem with living creatures, and let birds fly above the earth across the vault of the sky.” 21 So God created the great creatures of the sea and every living thing with which the water teems and that moves about in it, according to their kinds, and every winged bird according to its kind. And God saw that it was good.
24 And God said, “Let the land produce living creatures according to their kinds: the livestock, the creatures that move along the ground, and the wild animals, each according to its kind.” And it was so. 25 God made the wild animals according to their kinds, the livestock according to their kinds, and all the creatures that move along the ground according to their kinds. And God saw that it was good.
The phrase ‘according to their kinds’ is interpreted to mean something roughly analogous to the notion of ‘visibly different organisms’. It doesn’t really translate neatly to any level of the biological taxonomy.
In biology, there is essentially no mechanism that would prevent successive small changes in a population accumulating to produce larger changes: for many micro-evolutions to add up to macro-evolutions. This requires many generations: more generations than occur within a human lifespan, even for small organisms with short lifespans.
That’s why evolutionary theory does not predict that we would see large visible changes from one kind of living being into another on the scale of human lives, and we don’t. The fact that we don’t does not refute evolutionary theory, because it is not a prediction that evolutionary theory makes.
The concept of transitional fossils is related, but it probably deserves its own post.
For ease of navigation I will include links to each of the other posts in this series at the bottom of each post.
Why I think it’s important to understand evolution
Cosmogenesis, abiogenesis and evolution
Evolution and entropy
Facts, Theories and Laws
Radiometric dating and deep time
Four Forces of the Universe
Probability and evolution
Mitochondrial Eve and Y-chromosomal Adam
Complexity – irreducible and otherwise