How Animals recognize their Kins

11/08/2009

Maneka Gandhi

(Bihar Times) My mother has 56 cousins and while she may, I certainly cannot recognize all of them. My son Varun, on the other hand, never forgets a face, name or village, a gift he inherited from his father and grandmother.
Do animals recognize family members and ,like humans, react better to them?.
Many species can recognize not only their mates and children, but also siblings, aunts, uncles, or cousins. And from apes to insects, all species treat family better than other animals.
Animals use different methods of identification. Creatures that live in darkness recognise by touch. The mole cricket lives in intricate underground tunnels where mothers recognize children by feeling them with their antenna or mouth. Prairie Dogs also live in tunnels. When two meet, they touch teeth. Members of the same colony ,put their arms around each other and hug while strangers are sent packing. Spectrograms reveal how the call of each animal is distinct just as human voices are. Most monkeys, like their human descendants, can tell between the voices of different individuals in their social group.. Vervet monkey mothers pick out their young by voice alone. Vervet monkeys can also recognize relationships. In experiments where the call of one mother’s infant is played to the troop, many of them look in the direction of the mother whose baby has called.
Mothers and infants of most mammal species recognize each other vocally. Bats who live in caves with thousands of others, pick up on the voices of their kin and group members. Hyena mothers respond differently to the “whoop” calls of their cubs as well as identify the voices of other clan members. Elephants detect each other’s calls over 100 sq km or more. In fact elephants recognize ad remember hundreds of different individuals even after a gap of 12 years. When a voice is familiar, the elephant will approach and sniff the air with its trunk. If it is unfamiliar, it will adopt bunch up defensively with other members of the herd. Bottlenose dolphins also use “signature” calls to talk to relatives and friends.

Many mammals use smell to distinguish kin. The closer one’s aroma to that of another, the closer the relationship. When the tiny Belding's ground squirrels appear to be "kissing" they are in fact smelling each other’s facial scent glands. Once the squirrels have sniffed out close blood relatives, they are more likely to come to their aid. Full sisters are more likely to cooperate than half-sisters. Squirrels defend territories together by repulsing non-related intruders. Sounding the alarm is risky as the alarm sounder becomes fox’s first target while the others escape . Belding's ground squirrels are more willing to take the risk to help close kin rather than non kin.

Paper wasps construct colonies headed by a queen and her daughters. Kin identification is crucial because nests are frequently visited by other wasps with varying intentions. The visitors may be homeless relatives with nests destroyed by predators, or they could be intruders coming to steal eggs to feed their own larvae. Wasps distinguish between the two through their sense of smell. Each wasp can be recognized from the odour specifc to its nest.

Salmon know their siblings. Other migrating fish can even recognize fish from the same "neighborhood" as they swim through the vast ocean. Golden hamsters can tell relatives simply by giving them a good long sniff. Mice recognize relations by smelling their urine and avoid mating with them to prevent inbreeding. In fact mice and rats can remember the odour of another mouse they may have been in contact with for only 2 minutes, many days later.

Sheep and pigs distinguish individuals on the basis of the smell of their skin glands. Sheep goats, cows, horses and humans recognise the smell of their offspring within an hour of giving birth to them. Over the following days they also learn their voices and faces but initial recognition is only through smell. So once the mother sheep learns the smell of her own lamb, every other lamb encounters the full measure of her arsenal of head butts and bleats.

Rattlesnakes too display strong family bonds. Though to be solitary and aggressive, they are caring, family-loving reptiles. A study shows how adult timber rattlesnakes recognize siblings, even after being separated at birth, and females from the same litter associate more with each other than with other females.
When Spadefoot toad litters are born, a few tadpoles will develop huge, hardened jaws and become cannibals. But these cannibals are finicky about their prey! Sparing their own siblings, they gobble up strangers! Tiger salamander larvae also turn canniballistic. These not only spare their brothers and sisters but even their first cousins. Marbled salamander larvae relatives are well behaved among themselves, nipping one another only occasionally. However, they fight almost incessantly with non kin. Western toad tadpoles congregate in schools composed solely of their brothers and sisters.

Male bluegill sunfish seek out and socialize with individuals that smell like themselves. Researchers who created mixed broods in which some nest-mates were kin and others were unrelated, found that relatives actively sought and associated with siblings they had never net before.

Some species use a chemical-sensing mechanism. Tiny tentacle bearing marine invertebrates called hydroids , each the size of a pinhead, form colonies. When space is tight, expanding colonies converge at some point. If the two are unrelated they will create a living barrier of border cells. Alternatively one may attempt a takeover of the other provoking an all-out war wherein the frontline troops develop organs armed with stinging cells. However, if the two colonies are related, they happily merge.

Research suggests that plants too can recognize close relatives . Plants from the same mother are more compatible with each other than with plants of the same species from other mothers.

The fact that plants can recognize their kin was first demonstrated at McMaster University, Canada whose study found that the same species of wildflower grew aggressively alongside unrelated neighbors but were less competitive when they shared soil with their siblings. When unrelated plants share pots, they start growing more roots enabling them to grab water and mineral nutrients before their neighbors.. Sea Rocket showed more vigorous root growth when planted in pots with strangers than when raised with relatives from the same maternal family. The Forestry Sciences Laboratory in Alaska finds that pokeweeds and English plantains grow higher and faster when potted with full or half siblings than when potted with non-relatives.

Californian scientists have discovered that to guard against inbreeding, plants have mechanisms to recognize each other’s pollen and will not be fertilized by a gene-sharing plant. A sagebrush can recognise a genetically identical cutting growing nearby. What’s more, the two communicate and cooperate with one another to avoid being eaten by herbivores.