Feedback archive → Feedback 2014
Breeding unicorns
Are there any limits to the production of hybrid animals?
Published: 19 January 2014 (GMT+10)
T.S. wrote in asking us to help him spot the flaw in his friend’s reasoning about hybrids:
Hi, a friend of mine told me of an interesting discussion he had today with some people at university. He apparently won an argument saying because donkeys and horses have a different number of chromosomes, yet you can cross breed them to create mules, then you must be able to cross breed any animal family, he gave the example of a narwal and horse creating a unicorn.
I argued that because they are from a different “family” they cant possibly create offspring, but could not find sufficient evidence to convince him.
Any help with this would be much appreciated.
CMI’s Keaton Halley responds:
Hi T.S.,
Unfortunately, your friend’s argument is logically invalid. (To understand validity, please read Logic and Creation, especially the sections on validity and soundness. Or you can purchase Dr. Sarfati’s lecture, Leaving Your Brains at the Church Door?) Here’s an argument with the same form, and the conclusion obviously doesn’t follow from the premises. Compare:
- Donkeys and horses have different numbers of chromosomes but can produce offspring.
- Horses and narwhals have different numbers of chromosomes.
- Therefore, horses and narwhals can produce offspring.
- Sparrows and turkeys have different sizes but can lay eggs.
- Hamsters and kangaroos have different sizes.
- Therefore, hamsters and kangaroos can lay eggs.
See, one similarity doesn’t mean they share everything in common. If donkeys and horses can breed, that only shows that having the same number of chromosomes is not a necessary condition for breeding. But it does not prove that having a different number of chromosomes is sufficient. It shows that some animals with mismatched chromosomes can hybridize, not that all can. Successful reproduction depends on a whole lot of complicated biological factors, so we can’t tell whether two animal groups can hybridize just by counting their chromosomes.
One of these factors is called ‘synteny’ (i.e., gene order). When the chromosomes pair up in a donkey/horse hybrid during cell division, each daughter cell gets the same genes, even if the number of chromosomes is not exactly the same. This does not work for things like dogs and cats because the genes are dispersed differently among the respective chromosomes of the two species. Even if fertilization were possible among dogs and cats, the resulting hybrid would go into genetic meltdown before real embryogenesis even got under way.
Also, if crossing horses and narwhals really could produce a unicorn, then why hasn’t anybody bred one? I’d pay to see a real unicorn. Really, this example doesn’t serve your friend’s point; it just demonstrates the absurdity of his view.
One other thing: I wouldn’t say that the family level is always the boundary above which animals cannot hybridize. The Linnaean classification system doesn’t correspond perfectly with the biblical grouping of organisms into distinct ‘kinds’, so creationist scientists have tried to develop their own methods for determining what constitutes a biblical ‘kind’. In some cases, a kind may represent a larger group than a family, and in other cases it may represent a smaller group within a family. Our website contains lots of information about how creationists reach these conclusions. See our Speciation Q&A page, for example.
Hope that was helpful to you. God bless,
Keaton Halley
Reader’s comments
Feedback on comments of some of these articles as well as the articles themselves, would suggest that variability/adaptation as observed could be caused by various means which include mutations (errors on DNA -> loss of information), natural selection (elimination of the unsuitable -> loss of information), gene switching (switching on of a gene in preference over another in response to environmental conditions -> swapping, but retaining information) and maybe combinations of these.
As this article clearly demonstrates, what we learn from the ultimate Designer, we tend also to implement in an attempt of "improving" livestock. Obviously we cannot improve livestock, similarly neither can natural selction to do so.
However, there seem to be the odd chance that by re-combining "diverse" genetic information there may be a possibility to regain some of the original diversity of the "original" thus somewhat "improving" present commercial breeds.
What remains a challenge to comprehend is the switching mechnism - it can only happen at three destinct events during development - 1 at fertilization, 2 miosis, 3 post-miosis - of which only the 1st seem logical (@ miosis rather mutation, @3 no further alterations?), but then, what mechanism would trigger this response to the environment? It seems somewhat inconceivable.
Having the knowledge of the genome, would it be possible to recombine selective traits into a more environmentally adaptive breed by 'clever' selection from the already existing "menu" of specialized breeds, already "developed" by selecting for one trait only?
Also, there are other points at which genetic modification can occur, if you think about the field of epigenetics, for example.
If the faulty evolution science were ever proven, why did Ivanovitch fail to reproduce the missing link?
Reminds me that we're also still waiting for Jack Horner and Hans Larsson to produce a chickenosaurus despite their optimistic prediction about making it happen in only 5 years. See The Horner/Larsson quest: a “chickenosaurus” to publicly demonstrate evolution!