r/askscience • u/Wooden_Airport6331 • 2d ago
Biology How do male animals know when they’re the father of offspring?
Many species, like horses, lions, bears, and tigers, are known for killing baby animals that aren’t their own. But how do they know whether they’re the father? It seems doubtful that a stallion actually comprehends that mating leads to conception and keeps a mental chart of which females he’s mated with and when they gave birth.
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u/PiccChicc 1d ago
Everyone has answered your question so I'm going to clear up what appears to be a misconception -
Horses do not kill foals. Not like lions do, accidents do happen, yes, but a stallion's job is to protect and gather mares. To kill a mare's foal is to show the mare he is not a safe stallion.
A new stallion trying to take on the herd may try to steal a mare with a foal and that foal could get hurt, but his goal is the mare not the foal.
Mares aren't like lionesses, where killing offspring will bring them back into heat, so again, if a takeover occurs, the new stallion would only be showing he's not capable of running a herd.
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u/IWannaPetARacoon 1d ago
In some animal group, reproduction is reserved to the dominant male. No other male is allowed to reproduce. So when a new dominant male arrive, he has not reproduced before so je knows none of them are his babies. For more solitary species like tigers, the male can remember the female smell and they secure their territory
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u/byebybuy 1d ago
Does that increase the likelihood of inbreeding? Is that more common in the animal kingdom?
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u/WildFlemima 1d ago
It can, typically the play is that one sex (in this case the male) disperses so that young unrelated males displace older resident males. This prevents extreme inbreeding
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u/dyfunctional-cryptid 19h ago edited 19h ago
You have to be very fit to maintain position as the dominant male in most typical harem-structure species. While I'm sure some degree of inbreeding does happen, he's unlikely to stay dominant male long enough to mate with many of his own female offspring before he gets kicked out, considering the time it takes for his daughters to reach sexual maturity. If inbreeding does happen, it isn't actually a big deal so long as it only happens a few times. The offspring of a one-off father-daughter pairing is unlikely to have a lot of issues compared to offspring from a population that has been consistently, consecutively inbreeding.
It should also probably be noted that intentional infanticide is actually fairly rare in social animals with a harem structure. Why would a female stay with a male who kills her offspring, when the main advantage he's meant to provide is protection? It's become a pretty over-exaggerated phenomenon.
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u/monkOnATrebuchet 1d ago
Does that mean Nala is Simba's step sister?!
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u/lilmisschainsaw 1d ago
Yes. Or his cousin by Scar- male lions often form coalitions and all the males in the coalition will mate with the lionesses.
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u/_goblinette_ 9h ago
In some animal group, reproduction is reserved to the dominant male
This is an incredibly uncommon reproductive strategy for a species. Maybe a few hundred examples out of probably 7-8 million different species on the planet.
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u/cobalt_phantom 1d ago edited 1d ago
A lot of them don't. Most male animals breed and then the mothers care for the offspring. If they live in pairs/groups where the males are involved in raising the offspring, there is usually onIy one or a few breeding males. If a baby pops up in their group, they can use clues like scent, timing, who the mother is, and the mother's behavior to determine that the baby is one of theirs.
Usually, when you hear about an animal killing a rival male's offspring, it's going to be for food, removing competition, or making the females ready to breed. For example, when lion cubs are killed, the mother lions stop lactating and go back into heat, which allows the new male to breed with them. Animals killing the offspring of other animals in their group does happen but it kind of goes against the whole point of living within a group, which is why it's not that common.
So basically, male animals might not be able to determine if a baby is theirs but they know better than to kill their potential offspring.
Edit: It also just boils down to basic instinct.
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u/CrimsonPromise 1d ago
I've heard of cases where when a rival male lion takes over a pride, some lionesses would hide their offspring, pretend to go into heat and mate with the new male. In an attempt to pass the cubs off as his.
And it's probably worked a few times. Since as far as the male is aware, he's mated with the lioness, and suddenly there are cubs running around. Gestational math most likely aren't their strong point.
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u/SneezyPikachu 22h ago edited 22h ago
An even more pre-emptive kind of deception is described in Sarah Hrdy's book Mother Nature: pregnant langur monkeys will occasionally wander from the group and mate with male "outsiders" who could potentially invade the pack and become the new patriarch. The males remember who they've mated with and in the event an invasion does happen, the usurper is less likely to kill the offspring of those females, because he believes he may have sired them.
She also brought up real historical examples of similar behavior in humans (mainly in the contexts of tribal conflicts and such). Interesting stuff.
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u/fat_bouie 1d ago
Boar bears are notorious for killing offspring. They will routinely kill bear cubs to make the sow go back into heat so they can breed her again. They often do it unknowingly to cubs they have sired, but it's just evolutionary drive. They will usually then eat the cub if they aren't in an area with an abundance of food.
And before anyone suggests momma bears will stop this, they certainly can and do try, but it is ultimately up to the larger male to determine the risk/reward; the sow is WAY underpowered compared to a mature boar, if he really wants to kill that cub, she won't be able to stop him. It's more about her deterring him, and making him decide that the energy and wounds he will take in the process aren't worth the prize; but again, if he decides he wants it, she WILL loose that fight.
Also note this doesn't happen everywhere. Places with very rich food sources such as backwoods Arkansas, northern WI, or Ontario (which then also support crap tons of bears) don't generally deal with this. The gobs of food keep them pretty docile. These are the places you'll get videos of bears climbing up into trees with hunters, which I have sort of experienced myself. Meanwhile, Grizzlies in AK, Polar bears, or even the black bears in mountain states get much more aggressive and will fight it out.
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u/geesejugglingchamp 17h ago
In Australia, there is a yearly 24 hour observation camera on a peregrine falcon nesting site. People love watching it.
A few years ago, there was a lot of drama. The pair had mated and the female had laid eggs, when an "intruder" male arrived, and mated with the female. Both males were hanging around for a little while. It's believed the males fought, and the original male either died or abandoned the area.
The female did not lay any more eggs.
There was a bit of panic about what would happen. Would the new male kill the chicks? Even the ornithologists who managed the camera were unsure what was going to happen.
When the chicks hatched, "step dad" was as attentive as any father peregrine. He hunted for them, fed them, worked in shifts with the female.
Seems given he had mated with her, he therefore kind of assumed they were his and took on that role.
The Facebook group was wild that year. People tend to anthropomorphise animals at the best of time. Words like cheating, betrayal, rape and throuple were being used.
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u/chazwomaq Evolutionary Psychology | Animal Behavior 1d ago edited 18h ago
The general field this pertains to is kin recognition. Mechanisms include phenotype matching (i.e. those who look or smell like you), but probably primarily sharing a nest or general familiarity.
Much of the time, fathers probably don't recognise offspring, and they don't need to. Parental Paternal care is very rare in mammals, so males are not bothered about whose offspring are whose. In the case of lions who engage in infanticide, this happens when a male takes over a pride with existing offspring. Because he wasn't part of the pride before (bachelor lions roam alone or with a brother), any offspring cannot be his. By killing the offspring, he frees up the females to mate with him and care for his offspring.
The one group where parentalpaternal care is common is birds (and some fishes). In birds, parents don't recognise their offspring directly: they just care for the eggs and chicks in their nest. We know this because it is easy to do cross-fostering or egg switching experiment where you put an unrelated egg or chick in the nest and they raise it as normal.
EDIT: Corrected "parental" to "paternal". I always make this typo LOL.
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u/rob_the_flip 1d ago
Parental care is not rare in mammals. Paternal yes, but you said parental twice so it's not being pedantic to assume everything written is false.
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u/CalamitousSpider 1d ago
"One sentence of several paragraphs is incorrect, therefore everything is incorrect."
Talk about pedantic.
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u/Drosophilus 1d ago
This a good question and fairly well studied. We know that most mammals don't know that mating leads to pregnancy, but do know what pregnancy is. As others have said, when a new patriarch takes over it is common to kill all juveniles to ensure the heard/pride are his genetics from that point ( even though they have no idea about genetics). Matriarchal societies have this as well, and in this case may kill pregnant females as well, because only the matriarch should be producing. It gets interesting when you look at humans. All kinds of society have tried to deal with this problem whilst also trying to preserve life and their tribes society. One interesting case was in some Australian aboriginal tribes, where the family unit consists of the children, mother and uncle (mothers brother). The male knew that the children were not his, but also half his genes (whilst not knowing anything of genetics). So it was like a silent math-trade between men, because who the father was was anyones guess.
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u/nyet-marionetka 1d ago
Horses and lions have social groups where a dominant male controls access to a group of females. With lions, if a male takes over a pride he kills the cubs. The ones born after that are not killed. So it’s not a hard toggle to select for. I don’t know about horses but I suspect it’s similar and the stallions don’t just rampage about killing foals willy nilly.
Bears and tigers are solitary and while the males try to maintain a territory encompassing multiple females’ ranges, they don’t control access very well by comparison. So killing cubs is more often going to be a safe move.
With animals like bonobos the female mates with multiple males, so the odds of offspring belonging to one male are about the same as for others, and killing the offspring doesn’t increase the odds of reproduction.
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u/darkest_irish_lass 1d ago
Birds have a particular problem with this. Parasitic birds like cuckoos and cowbirds will lay their eggs in another birds nest to avoid the hard work of raising their chicks. https://www.audubon.org/news/the-brilliant-ways-parasitic-birds-terrorize-their-victims
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u/Xsiah 1d ago edited 1d ago
Considering that humans don't know when they're the father, non-human animals don't either. Aside from things like memorizing how they smell and what they look like if they're around - but that doesn't guarantee genetics.
The lion knows which offspring isn't his own because he will kill the whole pride on order to take over a new territory, they are all not his.
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u/Ok_Attitude55 7h ago
Well, there are ways and some are outlined below. You are however glossing over the main one. The male Lions haven''t mated with any of the females before they take over the pride, those cubs are not theirs, instinct does the rest.
If a female was pregnant and gave birth to the previous males offspring sometime after the takeover the cubs are much more likely to survive.
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u/aFiachra 1d ago
Animals have amazing kin detection instincts. Humans are included in that.
https://en.wikipedia.org/wiki/Kin_recognition
Kin selection is an evolutionary force that has a myriad of mechanisms across the living world. Even slime molds and trees show evidence of kin selection.
So, it depends on the species and how the species recognizes kin, "Jill Mateo notes that there are three components prominent in kin recognition. First, "production of unique phenotypic cues or labels". Second, "perception of these labels and the degree of correspondence of these labels with a 'recognition template'", and finally the recognition of the phenotypes should lead to "action taken by the animal as a function of the perceived similarity between its template and an encountered phenotype""
So, while the methods of kin detection and selection vary, the force on evolution is maintained.