Q for biologists re the breeding out of animal instincts

[Shanty Oilish]

I read somewhere that your basic chick, newly hatched, has a very specific idea in his head about predators flying overhead. If you rig up a hawk and pass it over, he's frightened. If you do a goose he's ok with that.
So I'm wondering if animals retain instincts for extinct enemies. Imagine showing them mockups of extinct critters, checking for recognition like a police artist with a witness---would they still show fear? (That'd help us figure out what some dinosaurs looked like!) Or does the instinct fade from a species over time? If it's that specific a reaction, that there's no trigger for it anymore, does it diminish in a species? Are there rules for this sort of thing or just hypotheses?

[carpetbagger]

1. The instinct fades over time.

Birds will retain fear of extirpated (locally extinct) predators of historical extinction (i.e., last 400 years or so). However, that fades over time. It's a difficult hypothesis to test, since the general morphology of predators remains the same over large chunks of time. For instance, if you were to put a large carnivorous mammal from 20 million years ago in front of mouse or some other small mammal, the mouse would do the same evasive behavior.

However, the behavior of flightless birds and mammals without predators indicates that when predators in general, or significant types of predators, are absent, the behavior extinguishes. There's a selection bias towards un-spooked animals when the benefit is food or territory and the cost is nothing.

[mike_c]

2. behavior is subject to natural selection too...

...especially innate or "instictive" behaviors. So when the selective pressure no longer exists, there is often a reproductive fitness penalty attached to exhibiting the behavior, e.g. an animal who "responds" to non-existant predators is diverting time and energy away from foraging, etc. Such behaviors eventually disappear.

[soothsayer]

3. What kind of instincts do us humans have?

I don't actually have any answers in mind, I just wonder cuz I know we must have some.

[Nikia]

4. We are mostly learning animals

I do remember from zoology class that we do have the instinct to like babies. We have some other subtle instincts as well influenced by hormones. Most of our behaviors are learned, however. We could probably learn not to like babies as well. I think that instincts are amazing. Learning is considered more complex but yet we are not born with a picture of food in our heads like so many other animals.

[HereSince1628]

9. I'd say humans are still a mix of innate behavior and learning.

True many of the things we think of with respect to our workaday life are learned. Modern jobs are quite diverse and their requirements aren't nearly uniform enough to provide an opportunity for selection. Rather unpredictability favors learning and selection of traits that facilitate learning.

Innate behaviors are to be most expected in the sorts of behaviors that everyone typically engages in, and which although the may be fine tuned, generally a performed on the first few attempts. Mating behavior is a reasonable places to look for innate behaviors in humans...

Another place is behaviors that support survival and for which second chances for learning my not be available. Most of us have experienced the innate behavior associated with human "snake detector" that illicits a quick step backward when we encounter things ranging from real snakes to crooked sticks in the grass.

[HereSince1628]

5. I suggest you look at titles in Evolutionary Psychology

Granted it is a field that remains controversial but so aren't all new things in science...

[Shanty Oilish]

6. Evolutionary Psych?

Cool. Giving me a category, that I can google all night, is the gift that keeps on giving. Thank you!

[MuseRider]

7. I know with horses

the instincts are intact and must be trained out of them. It is pretty easy to do and not traumatic. Behaviors are interesting things and much different. My horses that I have bred are all out of the same stallion with different dams. There are small differences between them but some behaviors seem constant. Every last one of them from the oldest to the youngest holds one of their front feet up while they eat and paw it in the air knocking everything over and occasionally getting them over the fence. My other horses do not do this and it is proving to continue even into the grand babies. Just one example. Funny thing.

[Shanty Oilish]

8. Thanks everybody - good sensible answers all

DUers!