Scientists from Germany and the USA found that common vampire (Desmodus rotundus) form a durable social ties is exactly the same as people — starting with the least expensive communication and gradually moving to more close — to that which they need. In the experiment, females vampires put them with familiar individuals and with the new — with the latter they are much less frequently shared meals, but always before this first courted. Article published in the journal Current Biology.
Building strong social ties require a long investment of time, emotion and other resources. In order to avoid investing in “wasted”, it usually increase over time: for example, any friendship starts with a not very frequent and not very close contact, and eventually develops into something more stable, provided if both parties, on the one hand, invested enough, and on the other receive from each other what they need.
Ls it just the same in the animal world — is not clear. On the one hand, animals are in fact unable to form strong social connections based on mutual investment. On the other, animals they can be like initially: roughly speaking, intra-species friendship animal completely passed the stage of Dating and not developed at all.
To clarify the matter decided by scientists under the leadership of Gerald Carter (Gerald Carter) from Ohio state University. This group has been studying the social ties of the common vampires and animals that can form strong social ties. In November, researchers found that friendship is an ordinary vampire does not break under different conditions: making friends in a lab with limited resources, females of this species have remained friends and will, when the need to nurture each other and care was not so acute.
For his new work, scientists 15 months followed two groups living in captivity vampires caught in different areas of Panama (19 and 8 individuals in the first and second group). At first the animals were kept in two separate groups: the first group within six months of restricted food so that they began to feed each other and care, the second group had only been together two weeks and had no strong ties to form did not.
After that, the vampires were divided into pairs for one individual from each group and four, in each of which were definitely already formed a strong pair. Finally, all vampires put together, add to them their born in captivity young.
As expected, in conditions of limited resources vampires are in fact often shared meals with familiar individuals: for example, in the familiar four vampires sharing a meal in 6 of 11 cases, and unknown in 2 cases out of 20. Thus in joint groups of animals, where he was familiar and unfamiliar individuals unfamiliar rarely began to share with each other food, but that tended, on the contrary, more often: on average, one wild vampire had a nursing friend of 2.7 and 7.2 caring individuals, and one individual that was born in captivity and 2.6 individuals who share food, and 14.4 individuals who care.
Courtship, therefore, were more frequent interactions than feeding, from which scientists have concluded that it is less costly. It is interesting that those individuals who began each other to feed, first to each other looked, as if promoting investment — in the same way as, for example, occur in people.
It is interesting that ordinary vampires can shape each other by strong ties not only for their own benefit but for the benefit of their offspring: the same group of scientists in 2017 showed that females of the common vampire suckle the children of their friends when they are absent.