[Gordon Love]

Gordon Love  asked the Naked Scientists:
   Hi Chris and everyone,

Firstly, I'd like to say how much I enjoy the podcasts each week and each month.  There's so little accessible science around for those of us who are not specialists.  Being blind, the podcasts really give me a lot of
pleasure.

My question relates to animals recognition of each other.  How, for example, does a dog know that an animal it sees in the distance is a dog rather than, say, a cat?  In other words, how does one species recognise members of its own and other species and then, having recognised it, react accordingly?

Many thanks,
Gordon Love
Stirling, Scotland

What do you think?

[CliffordK]

Certainly many predators, including humans, large cats, some bears, and many canine species have the ability to attack their prey with either short sprints, or at a distance (in the case of humans).

It is beneficial for animals to detect their predators, or in the case they are the predators, to detect their prey from a distance.

Many animals are very sensitive to smells, and can detect faint smells carried in the wind.  And, obviously some predators are smart enough to hunt downwind.

They are also sensitive to what they can see.  While some animals may not have the same color perception as humans, one can assume that many have similar acuity perception.  Eyes tend to be optimized to pick up movement.

Brain cells also tend to be optimized to recognize shapes, and to a large extent, critters.  Just like we can recognize a deer or a bear, it is likely that a deer would also have brain cells that would respond to other deer, a bear, or humans.

I wonder if there is something innate about grouping animals.  "All Bears may look the same"...  People may even have troubles detecting fine distinctions across racial boundaries.  But, this would mean that to some animals, all humans would look the same.

Now, dogs certainly can recognize certain individual people by both sight and smell.  Perhaps this is an adaptation as part of the breeding programs.  But, for example, my mother's dog can be left in the car, and will watch her from the car though a restaurant window, and reacts whenever she comes into view.  Likewise, humans have learned to recognize individuals among other species.

Much of our knowledge about cellular responses in the human brain was gained from testing in animal models due to the similarity among species (with the exception of language).  But, these abilities to recognize shapes, animals, and faces seem to be very fundamental in at least mammals.

The question is what happens once, say a predator recognition cluster of neurons is activated. 

In humans, we might jump first when we see a curved stick resembling a snake, then later think... SNAKE!!!!! or ...  oh, it is just a stick.

Animals may also run, observe, hide, or ignore, depending on the perceived dangers.

[Don_1]

Animals have the sight and perception they require to survive, the same as we do. Though in some cases they are very much better at it than we are.

Take a look at these Emperor Penguins:


Could you tell them apart? I certainly couldn't, yet a female Emperor Penguin can tell it's mate from the many thousands gathered in the nursery of the antarctic after months apart. How they do this is a miracle of nature.

Its not only predators and prey which need to tell each other apart. Zebra and Wilderbeast need to recognise each other as being of no threat, while the Cheetah needs to be able to recognise the difference between another Cheetah and a Leopard. To a Cheetah which has just made a kill, the approach of another Cheetah might mean having to chase off the intruder, but the approach of a Leopard would mean giving up the kill to the more powerful Leopard without a contest.

A Lion cub soon learns that the apparent slow and easy meal of a Hinge Back Tortoise is not quite all it seems. Once the Tortoise retreats into and closes its shell, there is no chance of the Lion getting anything. The lesson here is not to waste time and energy. In future, the Lion wont bother the Tortoise.

There is also the need, with some venomous animals, to recognise a real threat from a predator, from an accidental encounter and a worthwhile meal from a pointless venture. Where an accidental encounter poses no real threat, but the snake deems a lesson must be given, the snake may deliver a dry bite, ie a bite without venom. The production of venom is costly, so why waste it.

Most animals learn from their parents what is good food, what is not, what to take no notice of and what represents a threat. These lessons are taught mostly by example, but for some, the lessons are learnt from experience, instinct or the will to survive.

I think the only difference between our recognition of other species and other animals recognition, is that we have 'names' for species, where the rest of the animal kingdom does not. But we all rely on a visual shape, pattern and colouration stored in our memory. The ability to tell different animals (and plants, for that matter) apart is an essential to survival.