I have been asked many times to explain how so called “macro-evolution” works. There are of course many excellent books and articles online and off that cover this, but I thought it might be a good idea to have a blog post that explains it quickly and simply that I can refer to when asked. The following is adapted from a book manuscript (which might get published some day).
To see how macroevolution (the origin of new species) works, we can use a hypothetical animal, maybe one in the cat family. Let’s call it a lipard. And let’s say that there is a population of these large cat-like carnivores living on a large plain with plenty of prey animals. The lipards have gotten better and better at hunting thanks to several improvements (microevolution) in vision, muscle strength, digestion of meat, and other traits. And all of these positive changes eventually…
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All Things are Yours 
April 29, 2018 at 7:28 pm
Hi Heather, I just asked these questions on his blog as well. Maybe you can help:
OK, here’s a few questions that come up for me…
1) Aren’t genetic mutations nearly always detrimental and only beneficial in very rare cases? If so, it seems that a series of genetic mutations, even if it included some of the rare beneficial mutations, would still end up in extinction rather than a new and improved species. Even if 9 mutations were detrimental and one was beneficial, I imagine it would be very difficult to get an end result that was better.
2) The question with some proposed “evolutionary stages” is “how does this animal survive at the intermediate stage?” One example is that of a bird’s lungs in the evolution from a reptile to a bird. At the intermediate stages, the animal would be unable to breathe properly and die, thus never making it to the bird stage. Questions like these must be answered. Here’s an explanation I just found of the bird problem in particular. Maybe you can respond to it with an explanation: http://harunyahya.com/en/Darwinism-Watch/147849/the-unique-structure-of-avian
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April 30, 2018 at 1:19 pm
1. Actually, the vast majority of mutations are neutral in effect. Science fiction and other parts of popular culture have given people the idea that “mutation” means growing a third eye or something like that. While some mutations do have major detrimental effects like that, most have little to no effect at all. If a mutation is deleterious (meaning it reduces the likelihood of reproduction in an organism with that mutation), then, by definition, it is unlikely to spread to the rest of the population, as new alleles (genes and gene variants) can only be passed to future generations by inheritance–the organism must reproduce if that mutation is to pass on. Thus, while the vast majority of mutations are neutral, a few are deleterious and a few are beneficial (conferring an increase in likelihood of reproduction), so future generations are most likely to get the beneficial and neutral mutations, while the deleterious ones tend to get weeded out. However, small populations are more subject to extremes. Thus, when a population is drastically reduced, it is likely to undergo rapid adaptation (lots of beneficial mutations accruing rapidly) or extinction (lots of deleterious mutations accruing rapidly). In rare cases, like cheetahs, they regain their population numbers but maintain low genetic diversity.
2. Archosaurs (birds, dinosaurs, crocodilians and their relatives) all have some measure of unidirectional airflow in their lungs. In modern crocodilians, this is not total as it is in birds (and theropod dinosaurs before them), indicating that intermediate forms are perfectly capable of thriving.
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April 30, 2018 at 2:55 pm
I’ll add to #1 — we are just discovering epigentics as a means of new information for evolution too. Epigenetics is not mutational …at least at first. But if an epigenetic change results in something positive for an organism, it seems to drive mutuational change over time in that direction. I may be misunderstanding it as its not my expertise but it seems that epigenetics provides a scaffold which over time is filled in by mutuations that align with those changes.
http://epigenie.com/epigenetics-drives-genetics-straight-into-evolution-2/
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April 30, 2018 at 2:58 pm
About Lars’s #1 — he’s absolutely correct that everyone has mutuations from one generation to the next and most of these have almost no effect whatsoever on an organism. This is how we know for instance that you are related to someone from 500 years ago if you take a DNA geneaological test because there is a standard rate of mutation, so we can look at two people who are descended from one person and expect a certain amount of mutations on their Y chromosome from one another for instance if they are both descended from the same person but related to him.
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