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Author Topic:   What is the origin of instictive behavior to care for our kin?
Ragged
Member (Idle past 1840 days)
Posts: 47
From: Purgatory
Joined: 10-26-2005


Message 1 of 17 (522960)
09-07-2009 12:37 AM


It is common knowledge that there is an instinct which drives parents to care for their young. From evolutionary standpoint it is explained by the fact that parents are trying to make sure that their genes survive in their offspring. This same reasoning can be used to explain why people care about their brothers and sisters and the rest of their kin.

Of course, if we were to ask a parent why they care for their child they would not say "because I am protecting my genes", rather they would say something along the lines of "What do you mean "why"? Its my baby and I love it!"

So in this case, we are not motivated to behave in a certain way by evolutionary implications of our behavior, rather we are governed by an immediate instinct. From what I know that such a behavior would have to be genetic in nature, as opposed to being learned, much like eating when hungry. After all, a mother doesn't need to learn that caring for her child is the thing to do, she simply acts according to her instinct.

My question is how did this instinct come to be? Was there a time in evolution, when organisms didn't have this instinct? Would an organism X number of years ago not have an instinct to protect its offspring? Was it that at one point a mutation occurred which made organisms care for their offspring and this behavior made the organism so overwhelmingly more successful at making sure its genes survive that it quickly muscled out all other organisms that didn't have this instinct? Or was this instinct present from the very beginning. Did the very first cell ever to reproduce have an instinct to protect its offspring?


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Message 2 of 17 (522976)
09-07-2009 8:37 AM


Thread Copied from Proposed New Topics Forum

    
Dr Jack
Member (Idle past 393 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 3 of 17 (522984)
09-07-2009 10:09 AM
Reply to: Message 1 by Ragged
09-07-2009 12:37 AM


Single celled organisms do not, in general, care for their offspring. Neither, in fact, do most multicellular organisms (seen a tree looking after a sapling recently?) or most animals (fish? tapeworms? coral? most turtles?). In fact, looking after your offspring is a strategy isolated to a relatively small proportion of living things. Those livings take a varying degree of care for their offspring: we support our offspring for getting on for two decades in many societies, whereas a seahorse male merely incubates the eggs until release.

Offspring carers evolved from non-offspring carers, first through by providing short term, mild care and later by more and more complex caring behaviour. Each change providing an incremental benefit to their fitness.

Edited by Mr Jack, : No reason given.


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RAZD
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Joined: 03-14-2004
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Message 4 of 17 (522996)
09-07-2009 1:39 PM
Reply to: Message 3 by Dr Jack
09-07-2009 10:09 AM


Hi Mr Jack, Nice post.

Offspring carers evolved from non-offspring carers, first through by providing short term, mild care and later by more and more complex caring behaviour. Each change providing an incremental benefit to their fitness.

I would think that it allows young to be born earlier, thus reducing the impact on the mother (ability to avoid predators etc), and reducing the impact of death of the mother on the continued living young (with others around to care for it), and finally that it would allow earlier sharing of responsibility of feeding young from just the mother to other individuals.

Each of these would provide a small, but evolutionarily significant, increase in the ability of the mother and offspring to survive.

Enjoy.


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Ragged
Member (Idle past 1840 days)
Posts: 47
From: Purgatory
Joined: 10-26-2005


Message 5 of 17 (523000)
09-07-2009 2:26 PM
Reply to: Message 4 by RAZD
09-07-2009 1:39 PM


I would think that it allows young to be born earlier

How is that?


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InGodITrust
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Posts: 53
From: Reno, Nevada, USA
Joined: 05-02-2009


Message 6 of 17 (523004)
09-07-2009 3:21 PM
Reply to: Message 1 by Ragged
09-07-2009 12:37 AM


I hope one of the scientists here will correct me if I'm wrong, but I believe it is not well understood by science how instincts are encoded in DNA. But some genetic mutation probably started this instinct.

It seems to me that the parental instincts would have had to evolved a number of seperate times, as opposed to just once in a distant common ancestor, like the instinct to flee in the face of danger might have. There are fish and insects that just dump eggs, and then there is a spider that carries its little ones on its back, and the fish that shelters its young in its mouth. Of course mammals suckle their young, and most birds feed their young.

I guess I should note that I'm trying to understand evolution, but my true belief is that God gave this instinct.

Edited by InGodITrust, : No reason given.

Edited by InGodITrust, : No reason given.

Edited by InGodITrust, : No reason given.

Edited by InGodITrust, : No reason given.

Edited by InGodITrust, : No reason given.


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RAZD
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Message 7 of 17 (523006)
09-07-2009 3:43 PM
Reply to: Message 5 by Ragged
09-07-2009 2:26 PM


Hi Ragged, long time no see.

How is that?

http://en.wikipedia.org/wiki/Altricial

quote:
Altricial, meaning "requiring nourishment", refers to a pattern of growth and development in organisms which are incapable of moving around on their own soon after hatching or being born. The word is derived from the Latin root alere meaning "to nurse, to rear, or to nourish", and refers to the need for young to be fed and taken care of for a long duration.[1]

In bird and mammal biology, altricial species are those whose newly-hatched or -born young are relatively immobile, lack hair or down, and must be cared for by adults; closed eyes are common, though not ubiquitous. Altricial young are born helpless and require care for a comparatively long time. Among birds, these include, for example, herons, hawks, woodpeckers, owls and most passerines. Rodents and marsupials are altricial, as are cats, dogs and humans.


Without care these young would die, because they are not developed enough to be precocial, this level of development occurs after birth while under care of parents\group.

Taking an extreme example, in humans this allows the birth of the child while the brain is still small enough to fit through the birth canal.

http://www.springerlink.com/content/g183503303307587/

quote:
Most of the brain growth is completed by 5–6 years of age. At birth brain weight is 70% of an adult, 15% brain growth occurs during infancy and remaining brain growth is completed during preschool years.

Note that the skull bones are nearly fully developed but deform during birth to pass the canal and the sutures that bind the pieces in place form after birth:

http://www.landofskulls.com/site/1534698/page/893371

quote:
Did you know the human skull is almost at full size at birth? However, the cranium has not yet been compound together. In other words, the skull is flexible and distorted during birth therefore making it easier for woman to deliver a baby. And, after about 24 month after birth, the bones are fused together to form the adult skull.

The brain then grows to fill out the skull. Notice how this ties in to the source that says a human child is able to take care of itself at 8 to 11 years of age.

http://www.genefaith.org/ethgen/pages/databases/resources/humdevchart.html

quote:
child - 8 - 11 yrs - Capable of independent survival
adult human life - 18+ yrs

Enjoy.


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
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Modulous
Member (Idle past 392 days)
Posts: 7789
From: Manchester, UK
Joined: 05-01-2005


Message 8 of 17 (523008)
09-07-2009 4:05 PM
Reply to: Message 6 by InGodITrust
09-07-2009 3:21 PM


I hope one of the scientists here will correct me if I'm wrong, but I believe it is not well understood by science how instincts are encoded in DNA. But some genetic mutation probably started this instinct.

Well, you are nearly right.

The brain is the centre of instincts and brain development is encoded for in DNA.

It could be understood better, of course, which is why scientists are still trying to research ethology/genetics.


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Richard Townsend
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Posts: 103
From: London, England
Joined: 07-16-2008


Message 9 of 17 (523013)
09-07-2009 4:50 PM
Reply to: Message 4 by RAZD
09-07-2009 1:39 PM


quote:
I would think that it allows young to be born earlier, thus reducing the impact on the mother (ability to avoid predators etc), and reducing the impact of death of the mother on the continued living young (with others around to care for it), and finally that it would allow earlier sharing of responsibility of feeding young from just the mother to other individuals.

Also allows mother to produce fewer offspring as parents give greater protection from predators.


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Dr Jack
Member (Idle past 393 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 10 of 17 (523014)
09-07-2009 5:28 PM
Reply to: Message 4 by RAZD
09-07-2009 1:39 PM


I would think that it allows young to be born earlier, thus reducing the impact on the mother (ability to avoid predators etc), and reducing the impact of death of the mother on the continued living young (with others around to care for it), and finally that it would allow earlier sharing of responsibility of feeding young from just the mother to other individuals.

I don't think that's true. The many species that scatter their young to the currents generally produce very, very small undeveloped young that are highly disposable. In fact, if anything, the opposite is true: cared for young represent a much larger investment of energy than scattered young. The two approaches are referred to as K- and r- strategies, but I can't remember right now which is which. I shall look it up tomorrow.


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RAZD
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Posts: 20156
From: the other end of the sidewalk
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Message 11 of 17 (523019)
09-07-2009 5:55 PM
Reply to: Message 10 by Dr Jack
09-07-2009 5:28 PM


Hi Mr Jack,

The many species that scatter their young to the currents generally produce very, very small undeveloped young that are highly disposable.

Yes, but these young are still capable of living on their own - they are still "precocial" in that regard (if the word can be applied to larvae), and - it seems to me - the grown organisms are generally smaller than those that do care for their young, even minimally.

I was thinking more of the contrast between minimal care precocial animals and maximal care altricial animals, rather than in general to all organisms, where the altricial species are generally less developed than the similar precocial species.

http://en.wikipedia.org/wiki/Precocial

quote:
In Biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. The opposite developmental strategy is called "altricial," where the young are born helpless. Extremely precocial species may be called "superprecocial." These three categories form a continuum, without distinct gaps between them. Precocial species are normally nidifugous, meaning that they leave the nest shortly after birth.

The span between precocial and altricial species is particularly broad in birds. Precocial birds, including many ground-nesting species, have offspring that hatch with well-ossified skeletons, with good sight, and covered with feathers. Very precocial birds can be ready to leave the nest in a short period of time following hatching (e.g. 24 hours). Many precocial chicks are not independent in thermoregulation (the ability to regulate their own body temperatures), and they depend on the attending parent(s) to brood them with body heat for a short period of time. Precocial birds find their own food, sometimes with help or instruction from the parents. Examples of precocial birds include the domestic chicken, many species of ducks and geese, waders, rails and the Hoatzin. The most extreme, superprecocial birds are the megapodes, where the newly-hatched chicks dig themselves out of the nest mound without parental assistance, and fly on the first day after hatching.


Many precocial birds get minimal care from parents, similar to crocodiles, turtles, snakes and lizards

In fact, if anything, the opposite is true: cared for young represent a much larger investment of energy than scattered young.

We also see precocial animals that are large investments of energy, and which receive minimal, if any, care after birth, so it's not a strict linear relationship, more of a scattered one.

Perhaps

Edited by RAZD, : splink


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
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Ragged
Member (Idle past 1840 days)
Posts: 47
From: Purgatory
Joined: 10-26-2005


Message 12 of 17 (523038)
09-07-2009 9:21 PM
Reply to: Message 7 by RAZD
09-07-2009 3:43 PM


Hi RAZD,

That makes sense. Its like, the time that organs complete their development after birth decrease the time that has to be spent in the womb, which allows offspring to be born sooner. And its allowed by the fact that parents takes care of their children for some time after birth. Sound about right?


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Ragged
Member (Idle past 1840 days)
Posts: 47
From: Purgatory
Joined: 10-26-2005


Message 13 of 17 (523040)
09-07-2009 10:04 PM


Reproduction method relates to care?
It seems that animals that don't have the luxury (or rather the capacity) to lay thousands of eggs over their lifetime and hope for some of the them to survive due to luck, need to make sure that most of their eggs survive to become self supporting organisms. Because larger animals usually don't produce as many fertilized eggs they have to make as many of the count as they can. They have all their eggs in one basket so to speak. Which is why they care for their young.

Not to say that there are no counter-examples to this principle. (which there probably are)


    
Dr Jack
Member (Idle past 393 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 14 of 17 (523054)
09-08-2009 5:31 AM
Reply to: Message 11 by RAZD
09-07-2009 5:55 PM


Yes, but these young are still capable of living on their own - they are still "precocial" in that regard (if the word can be applied to larvae), and - it seems to me - the grown organisms are generally smaller than those that do care for their young, even minimally.

Isn't that a change of position from your first post?

I think if you plotted them both graphically, you'd determine that the very largest animals do, indeed, care for their young (see, blue whales) and the very smallest do not. This part of the pattern makes sense, it's much more difficult for a microscopic organism to effectively care for young both in terms of the advantage it can give, and the requisite behavioual repetoire to provide that care. Conversely, if you want to be very, very large it's going to be easier to get part way there, right?

But in the middle there would be a huge spread of animals in which no clear pattern occurs. There are certainly plenty of large animals that do not care for their young, and small animals that do. So it seems to me that you've identified the wrong key characteristic here.

Organisms which do not care for their young can produce more of them, usually massively more. If the environment allows it these organisms can massively increase their numbers in a very short time (these are r-strategists), meaning they can take advantage of highly variable environments. These environments* select for fast-growing, short lived, small body sized, early breeding, semelparous (i.e. organisms that breed only once) organisms that produce large broods.

In contrast we have K-strategists. K-strategists aim to maximise their eventual population size. They cannot increase their populations so quickly, but their young are much more likely to survive and prosper. There are found in stable environments*, which select for slow-growing, large body size, late breeding, iteroparous (i.e. breeding multiple times), long lived organisms. These are also the organisms that will tend to provide maternal care.

The chapter on 'Principles of Population Ecology' in Pianka's Evolutionary Ecology covers K- and r- strategists pretty well.

* - w.r.t. K- and r- strategists, the environment should not be considered just as the environment in a single area. Many r-strategists also act as early colonists of new areas, whether fresh lava flows, where a tree has fallen in a forest, or whereever.


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caffeine
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Message 15 of 17 (523091)
09-08-2009 10:55 AM
Reply to: Message 10 by Dr Jack
09-07-2009 5:28 PM


K- and r- mnemonic
The easy way to remember the difference is alliteration (at least phonetically:

K = quality
r = rate


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