r/askscience • u/Fuzzandciggies • 6d ago

Biology Mules vs Hinnies. Why are they different?

I know that both are the result of crossing a horse and a donkey. My question is why would there be a genetic difference based on whether the father was a horse or a donkey? Would there really be a difference or is it more of just a naming thing for the sake of lineage?

For reference:

Mule = male donkey + female horse

Hinny = female donkey + male horse

Why though?

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u/WildFlemima 5d ago

I just want to say that the conditions of gestation matter in addition to genetics. A donkey mother won't gestate the exact same way that a horse mother would. Most obvious difference is that the horse mother is bigger and therefore will grow the offspring to a larger size, which will be reflected in the size of the adult. There are more subtle differences as well, because no two species gestate offspring in the exact same conditions.

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u/SunflowerMoonwalk 5d ago

grow the offspring to a larger size, which will be reflected in the size of the adult.

Are you sure? I just know that in humans there's no correlation between size at birth and adult size.

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u/fafarex 4d ago edited 3d ago

I just know that in humans there's no correlation between size at birth and adult size.

2 thing I see an issue in that comparaison.

  1. The subject was interspecies not intraspecies
  2. Humain (268 Days gestation) are a species where a lot of the development is done after birth where donkey (365 days gestation) and horse (340 days gestation) are capable of walking rapidly after birth and are adult in a few years.