biological significance and evolutionary mechanism of altruistic behavior



Reprinted from: Zhihu, Biowood
Computational biology ENFP


altruistic behavior,
is everywhere in biosphere ,
As far as human society is concerned, mothers protect their children, and firefighters save people and lose their lives. Altruistic behavior is everywhere and well-known to us.
However, in the animal and plant world, does altruistic behavior still exist?
The core of Darwin's theory of biological evolution is the theory of natural selection. This theory tells us that in the process of survival competition, species gradually produce new species through the action of natural selection and realize the evolution of organisms.
Examples of survival competition can be seen everywhere in nature. For example, before entering the water, in order to determine whether there are seals in the water, they often push each other into the water and let their companions be scapegoats.
The monkey king in the forest has groups of wives and concubines, but he does not allow other male monkeys to "touch" one of its concubines.
and other,
are typical self-interest behaviors.
However, survival competition is only one aspect, and there are also altruistic behaviors of mutual assistance and love in nature.
1. The biological basis and significance of altruistic behavior:
"altruistic behavior",
Through the altruistic object and purpose,
can be divided into three forms: "kindness altruistic", "reciprocal altruistic" and "pure altruistic".
(1) "Celebrity and altruism".
is a biological individual with blood ties, and
provides help or sacrifice to its relatives.
According to the "kind selection" theory, the evolution of organisms,
depends on "maximizing gene genetic frequency", and can provide "kind-altruistic" species and have obvious evolutionary advantages in survival competition.
is also this.
"kinship altruism" behavior is a relatively common behavior in the entire biological world and is especially common in human society.
(2) Unlike "kind altruism", "mutual altruism",
is to provide help to biological individuals without kinship ,
, but this help is rewarding.
means that the reason why biological individuals want to help other organisms is because they expect to receive future rewards (retribution).
For example,
In Africa, some bats ,
may vomit some blood to their dying partners, but they also hope to repay their kindness in the future.
and, they will not continue to give blood to individuals who are unrepaying their kindness.
(3) The third altruistic behavior,
is "pure altruistic".
is an altruistic behavior that does not count for any reward.
This is a very special altruistic behavior. Many biologists such as Lawrence, , Wilson, believe this is a "group selection theory".
They believe that
inheritance and evolution, at a higher level of biological population, when the altruistic behavior of biological individuals is beneficial to the interests of the population, this behavioral characteristic may be retained with evolution.
Certain creatures, such as gazelle , may use their own strength to attract hunters and preserve the safety of the group when they are threatened.
This behavior is not common in nature, but it also happens from time to time.
(The figure below reveals the classification of these three altruistic behaviors, omitted)

Therefore, the biological significance of altruistic behavior,
can also be described from three aspects. From the "kind altruistic" level,
altruistic behavior can allow organisms to sacrifice to protect relatives, and this altruistic behavior can maximize the efficiency of organisms' reproduction.
Since the evolution of organisms depends on "maximization of genetic frequency", this altruistic behavior can maximize survival advantages.
From the "reciprocity and altruism" level, altruistic behavior can increase the survival chances of species.
Since the species in the weak can obtain more help and continue to help other organisms in the future. This altruistic method can increase marginal utility and enhance the chances of group survival.
From the "pure altruism" level, this is a factor that evolves completely from the evolution of the group.
It is precisely because of the emergence of "pure altruistic" behavior that the survival chances of the entire group have been improved, which plays a very important role in the process of group selection.
2. Evolutionary mechanism of altruistic behavior
In early evolutionary theory, the evolutionary mechanism proposed by Darwin (C. Darwin) is the most popular. He once pointed out that after a natural selection process, organisms with altruistic nature are more likely to keep their species alive. The idea of
has been confirmed by the famous contemporary sociobiologist E. O. Wilson.
More than 100 years after Darwin's evolutionary theory was published, Hamilton, an evolutionary biologist at the University of Cambridge, proposed a theory of kinship selection based on generalized fitness.
The core is to place evolutionary units at the genetic level.
The essence of altruistic behavior is that altruistic genes help relatives with common genes through their carriers, thereby indirectly transmitting themselves to maximize genes rather than individual interests.
...
Specifically, when the product of the benefit b brought to the recipient by
and the relationship degree r of the two is greater than the altruistic cost c, that is, rb c,
altruistic gene can evolve.
generalized concept of fitness,
successfully explains the altruistic behavior of social insects, emphasizing that altruists only provide help or sacrifice for their relatives, and are proportional to the degree of closeness.
The closer the kinship relationship between individuals, the stronger the altruistic tendency between them, because the closer the relationship, the more the same genes are.
The altruistic behavior of social insects exists and evolves because the organism is just a carrier of genes. Selfish genes control individual behaviors, so that their copies (replicas) can be preserved and reproduced in large quantities. The proportion of close relatives with common genes is large, which determines that close relatives should adopt altruistic behaviors when necessary.
The essence of the three altruistic behaviors,
is a better continuation of genes.
As Doggins 's selfish gene theory believes that individuals are under the control of genes, whether altruistic or selfish.
Organisms are just gene reproduction and functional units, gene carriers and machines controlled by genes.
"One of the most prominent features of the successful gene is its ruthless selfishness. The selfishness of this gene often leads to individual selfishness.
However, we will also see that in order to achieve their selfishness more effectively, some genes will breed a limited altruism in some special circumstances."
This view can be well explained in three fields: kinship altruism, reciprocity altruism, and then pure altruism,
altruism theory. This is also the essence of the evolutionary mechanism of altruistic behavior.
