Hunting laws in many countries and U.S. states prevent mother bears from being hunted while they are accompanied by their cubs. In Sweden, that seems to have artificially selected for mother bears that spend an extra year raising their cubs:
Female bears generally spend either 1.5 or 2.5 years with their young. In many ways, the pressures of bear life favor the shorter option — a mother with cubs cannot mate, so the more time she spends with each litter, the fewer offspring she'll have over her lifetime.
But a new study [open, DOI: 10.1038/s41467-018-03506-3] [DX] of brown bears in Sweden has found a surprising trend: More and more mothers are spending the extra year with their cubs.
"There's about a 30 percent increase in females staying to care for young for an extra year," explains Fanie Pelletier, an ecologist at Sherbrooke University in Quebec, and an author on the study published Tuesday in the journal Nature Communications. "Early on, in the '80s, almost all females stayed with their young for 1 year and a half," she says. "It's only since 2005 that we have witnessed this increase in the population [that are] staying with their young the extra year."
The trend is tied to a hunting regulation that protects family groups from hunters. It's illegal to shoot mother or cubs when they are together.
"For females, if you leave your cubs at one year and a half, then you become a target during the next hunting season," explains Pelletier. But "if you stay for a bit longer with your cubs, you're protected an extra year. The hunting is filtering out the females that keep their young for a smaller amount of time."
Abstract:
As an important extrinsic source of mortality, harvest should select for fast reproduction and accelerated life histories. However, if vulnerability to harvest depends upon female reproductive status, patterns of selectivity could diverge and favor alternative reproductive behaviors. Here, using more than 20 years of detailed data on survival and reproduction in a hunted large carnivore population, we show that protecting females with dependent young, a widespread hunting regulation, provides a survival benefit to females providing longer maternal care. This survival gain compensates for the females' reduced reproductive output, especially at high hunting pressure, where the fitness benefit of prolonged periods of maternal care outweighs that of shorter maternal care. Our study shows that hunting regulation can indirectly promote slower life histories by modulating the fitness benefit of maternal care tactics. We provide empirical evidence that harvest regulation can induce artificial selection on female life history traits and affect demographic processes.
(Score: 4, Funny) by coolgopher on Thursday March 29 2018, @03:20AM (2 children)
This is bearly news...
(Score: 3, Funny) by aristarchus on Thursday March 29 2018, @07:10AM
Have you never heard of Jew-bears-ish mothers? They not only kill Nazis, but the keep calling them up to ask why they are not married yet, and why that haven't taken the LSAT or the MCATs yet. Oh, our anti-semitic posters will be mauled, clawed, and branded well before they have to worry about Jew-Bear_mothers.
(Score: 4, Touché) by DannyB on Thursday March 29 2018, @01:43PM
It is big news to people who don't believe in eviloution. Mother bears spending more time with their cubes is just exhibiting good family values.
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(Score: 2) by frojack on Thursday March 29 2018, @06:05AM (7 children)
When you consider how short the time span these hunting laws have been on the books the change in behavior happening this quickly is pretty amazing.
As a lady the law in my state was that a sow shouldn't be shot if it was with Cubs less than a year old, which you can reliably tell by size of the cub.
I don't know when the law changed but let's assume 20 years ago.
The average life span of a black bear is 10 years. 20 years is not uncommon. So within one or two generations the bears behavior has changed. That is FAR TOO QUICKLY for natural selection to change the Bear's herd behaviour.
This seems more like learned behavior to me.
No, you are mistaken. I've always had this sig.
(Score: 2) by coolgopher on Thursday March 29 2018, @06:25AM
Actually, I'd say it depends entirely on how effective the hunting is. If the culling rate was 100% of the 1.5yr-cub-rearing population, it could be a trait which is effectively wiped out in a single generation.
Looking at actual numbers from various sources, it seems there are ~3000 bears in Sweden. I find only one article[1] discussing the culling rate, which puts it at ~10% yearly. With the 1.5yr-cub-rearing population being roughly twice as likely to be culled, it does seem plausible that it's sufficient to influence behaviour. There are some compounding probabilities involved here, but I can't be bothered to work out how to calculate it properly. Feel free to do the real maths and post the results :)
[1] https://www.thelocal.se/20150428/brown-bear-population-at-risk [thelocal.se]
(Score: 2) by marcello_dl on Thursday March 29 2018, @06:45AM (3 children)
>When you consider how short the time span these hunting laws have been on the books the change in behavior happening this quickly is pretty amazing.
Only if you insist in not considering concepts like karma and providence, implying that all mutation is random and selection a function of time. This has nothing to do with religion, in fact it becomes about religion only when you pick Darwin over Lamarck because it makes less assumptions. Everything should be made "as simple as possible, but not simpler".
Let's face it, when you get old enough, something about the random impersonal universe does not compute.
(Score: 1, Funny) by Anonymous Coward on Thursday March 29 2018, @07:25AM (1 child)
That's just selection bias, the rest of us just die young in nihilistic apathy.
(Score: 2) by Bot on Friday March 30 2018, @11:19PM
> That's just
selection biasprovidence: the rest of us just die young in nihilistic apathy.FTFY
Account abandoned.
(Score: 3, Interesting) by stormreaver on Thursday March 29 2018, @12:03PM
Since the notion of Karma and Providence are religious nonsense (Karma less so than Providence, as an argument can be made linking Karma and Conscience), your posting has everything to do with religion.
Unless bears have a heretofore unknown understanding of human hunting laws, this is most likely the result of hunters reducing the number of bears that possess a weaker genetic predisposition to raise their young over longer periods; leaving a larger pool of reproducing bears with a stronger genetic predisposition to raise their young over longer periods.
In other words: Darwinian Evolution.
(Score: 3, Interesting) by wisnoskij on Thursday March 29 2018, @02:19PM (1 child)
Considering the lifestyle of bears and the nature of hunters, this seems unlikely. When a bear gets shot at by a hunter, most of the time it ends up dead. So unless we assume some bear social network, and assume that the bears miss the dead ones and then compiled the statistics learning that when you are not feeding your cubs you statistically are at a huge risk of mortality, I see no way that such learning could occur.
Not that it is necessarily really evolution. This could just be the result of some population pressure, they might just be deciding to care for their young longer because they need it. Or maybe there are too many bears the they are trying to self limit?
Or maybe it is selection bias in the statistics? The only bears in their study are the easiest ones to hunt/track, and all the ones that were that easy to track and did not have cubs were killed.
(Score: 2) by Joe Desertrat on Friday March 30 2018, @09:28AM
Evolution would be a change in the species as a result. This is merely a drift in the genetic disposition of the population towards those who rear their cubs for longer. Likely it has always had both, but those without cubs get killed off quicker. Should hunting pressure suddenly cease, the population would probably rebound quickly in the opposite direction as bears with a shorter period rearing cubs would tend to breed faster and/or feed themselves easier.
(Score: 5, Funny) by GreatAuntAnesthesia on Thursday March 29 2018, @08:43AM (1 child)
Yet another breathless so-called "science journalism" article deriving conclusions from research that is only half complete.
Wake me up when they've finished the human trials.
(Score: 0) by Anonymous Coward on Thursday March 29 2018, @09:39PM
If you're only an Aunt I don't know if you want them to do human trials. Better put an extra $20 in your niece and nephew's birthday cards, make sure they come around more often.
(Score: 2) by realDonaldTrump on Thursday March 29 2018, @12:48PM (1 child)
I am a big believer in the Second Amendment. I'm not a hunter and don't approve of killing animals. But, good to know hunting is bringing back MOTHERHOOD!
(Score: 2) by DannyB on Thursday March 29 2018, @01:45PM
If hunting bears helps protect mother bears, then hunting them with automatic weapons should help protect bear populations even more! Sign an executive order today! (But don't read it first, assuming you can read.)
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(Score: 3, Interesting) by Translation Error on Thursday March 29 2018, @01:37PM (1 child)
(Score: 2) by DannyB on Thursday March 29 2018, @01:46PM
These fish aren't going to fly because what you suggest can be used as evidence to support the idea that evolution could be real.
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(Score: 2) by meustrus on Thursday March 29 2018, @02:03PM (2 children)
Hm...could this be a universal selective force towards staying with the young longer? Could there have been a part of human evolution that selected for mothers caring for children longer, leading to more space for human children to need constant attention? That could happen if other humans were more likely to protect mothers than unattached women. Which is probably true because mothers have more pronounced sexually attractive dimorphic traits (large mammaries and hips).
By extension, could we be starting bears on the same path? If this continues for a few hundred years, will bears become smarter due to an increased ability to endure the early years of intelligent curiosity being extremely dangerous?
If there isn't at least one reference or primary source, it's not +1 Informative. Maybe the underused +1 Interesting?
(Score: 3, Touché) by Anonymous Coward on Thursday March 29 2018, @02:23PM (1 child)
So how long until the bears obtain firearms and start hunting humans?
(Score: 4, Funny) by Dr Spin on Thursday March 29 2018, @02:59PM
This is Sweden.
America already has the right to arm bears (its in the Yogi amendment).
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