Evolution

QIP CD Cell Project IIT Guwahati 2009-10

NATURAL SELECTION

Daily and hourly scrutinising; throughout the world, every variation, even the slightest; rejecting that which is bad, preserving and adding up all that is good; silently and insensibly working, whenever and wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life.


DARWIN'S THEORY

Darwin came to understand that any population consists of individuals that are all slightly different from one another, those individuals having a variation that gives them an advantage in staying alive long enough to successfully reproduce are the ones that pass on their traits more frequently to the next generation.

Subsequently, their traits become more common and the population evolves.

Darwin called this “descent with modification”.


TELL-TALE SIGNS OF EVOLUTION

Our emotional behavior follows the pattern that arealready visible in lower animals.

The curling of lips into a sneer maybe a relic of the snarling action designed to show the teeth to an enemy when the teeth were still used as weapons.

Our lives are still dominated by functions imposedon us as a result of our animal ancestors.


Our moral sense It is a product of interaction between social instincts and developing

intelligence .

Darwin believed that groups will more socially developed social instincts would displace others in which those instincts were less powerful. He noted that in many ‘primitive’ tribes, the willingness to co-operate with each other is confined to the tribal group-outsiders don’t count as amoral universe.

This one was consistent with the view that the social instincts were built up for the benefit of the group. As the size of our societies have increased we have inevitably been learn to generalize the moral theories designed to convince us that respect for others is an absolute good.

Adaptation explains why our ancestors had evolved characters that separated them from apes. The apes have remained apes because they have retained their ancestor lifestyle in trees, their forelimbs have thus continued to be adapted for grasping branches. Our own ancestors moved out of the trees, stood upright as means of getting about in open plains.

This in turn freed their hands for exploring the environment and for using sticks and stones as primitive tools. Therefore our intelligence is a byproduct of unique shift in lifestyle by our ancestors. In their new way of life, something called natural selection favored those individuals who walked upright and in turn promoted the increase of intelligence within a population that now had better opportunity to exploit that faculty.


Evolutionary Psychology

• Culture is created by the communal mind, and each mind in turn is the product of the genetically structured human brain. Genes and culture are therefore inseverably linked.

• But the linkage is flexible, to a degree still mostly

unmeasured. The linkage is also tortuous: Genes prescribe epigenetic (besides + genetic) rules, which are the neural pathways and regularities in cognitive development by which the individual mind assembles itself.

• The mind grows from birth to death by absorbing parts of the existing culture available to it, with selections guided through epigenetic rules inherited by the individual brain.

• Evolutionary psychology is the combination of two sciences -- evolutionary biology and cognitive psychology

Evolutionary psychology is the approach of explaining human behavior based on the combination of evolutionary biology, anthropology, cognitive science, and the neurosciences. Evolutionary psychology is not a specific sub field of psychology, such as the study of vision, reasoning, or social behavior. It is a way of thinking about psychology that can be applied to any topic within it.

• Evolutionary psychology is the science that seeks to explain through universal mechanisms of behavior why humans act the way they

• Evolutionary psychology seeks to reconstruct problems that our ancestors faced in their primitive environments, and the problem-solving mechanisms they created to meet those particular challenges.

• From these reconstructed problem-solving adaptations, the science then attempts to establish the common roots of our ancestral behavior, and how those common behavioral roots are manifested today in the widely scattered cultures of the planet. The goal is to understand human behavior that is universally aimed at the passing of one's genes into the next generation.

At the core of evolutionary psychology is the belief that all humans on the planet have innate areas in their brains which have specific knowledge that help them adapt to local environments.

These areas are highly specialized, and only activate when the information is needed. These areas give the brain specific algorithmic (step by step) instructions that have evolved from our ancestral pasts to adapt to all situations, including the situations that we face today.

But since our brains were conditioned to live in deep history i.e., our ancestral past, and not to modern conditions, the result is a gray area between genes and culture that drives some humans into depressive states.

Robert Wright• "Whether burdened by an overwhelming

flurry of daily commitments or stifled by a sense of social isolation (or, oddly, both); whether mired for hours in a sense of life’s pointlessness or beset for days by unresolved anxiety; whether deprived by long workweeks from quality time with offspring or drowning in quantity time with them – whatever the source of stress, we at times get the feeling that modern life isn’t what we were designed for."

• The functional organization of the body has been elucidated primarily by the direct examination of morphology. A detailed analysis of the structure and composition of our organs and tissues has resulted in an excellent understanding of their purpose. Unfortunately, this has not been the case with the brain. The gross morphology of the brain appears to have little connection with its functional properties. Although we have a fair understanding of nerve cells--the primary constituents of neural tissue--the properties of the brain clearly come from higher order assemblages of such cells, not just the cells themselves.

• This is just as true of organs like the heart as it is of the brain. Because nerve cells can rapidly change state (e.g., their firing rate), because such state-changes involve little energy, and because they can be well insulated from their neighbors, it is possible for a nerve cell to be in one state, whereas some of its close neighbors may be in completely different states. This is in marked contrast to, say, muscle cells. If one muscle cell is involved in a contraction, then nearby cells almost certainly are as well. Neural tissue is quite different. Even the individual states of nerve cells in a network depend critically on the topology of the network itself. Further, assemblages that are actually distinct may have a complex three-dimensional distribution that can be very difficult to untangle. These properties of neural tissue make it exceedingly difficult to "see" the morphology of neural assemblages--with few exceptions, the network topology of virtually our entire brain is currently "invisible." It exists at a scale above the individual cell, but well below that which can be teased apart with any imaging technology currently available. Until recent decades, much of our immune system was similarly "invisible."

• Evolutionary psychology offers one way around this technological limitation. If researchers had a sound basis for proposing brain functions a priori, they could then seek indirect evidence that brains in fact have these functional properties. Philosophers and scientists had long wondered why living things are made up of an amazing array of beautifully designed mechanisms, an organization which non-living things completely lack. Why is it that entities that reproduce manifest overwhelming evidence of design, but entities that don't reproduce are utterly devoid of the same? As Darwin and Wallace first perceived, the association of reproduction and design is not accidental. Evolution by natural selection is currently accepted as the only process whereby entities can acquire functional properties. Functional organization is the consequence of the reproductive feedback that characterizes natural selection. If a population of reproducing entities (hereafter organisms) varies in some trait, if the variations can be passed on to offspring, and if, as a consequence of possessing a particular variant, an organism produces more offspring on average than organisms that lack that variant over evolutionary time, then the population will come to consist solely of organisms possessing the reproductively efficacious variant trait. In this way, populations of organisms will tend to acquire traits that facilitate reproduction and lose traits that hinder reproduction.

• Over the last 200,000 years, humans regularly encountered spiders and snakes, creatures whose toxins would have significantly impeded the reproduction of individuals unlucky enough to get injected with them. Over the last 100 years, humans have regularly encountered automobiles, encounters that also can seriously impede reproduction (e.g., by getting run over). Because 200,000 years is long enough for humans to evolve protective mechanisms, but 100 years isn't, we can predict that humans may well possess an innate aversion to spiders and snakes, but not to automobiles--even though far more people are currently killed by cars than by spiders or snakes. Once we have firmly established that avoiding spiders and snakes would have reliably facilitated the reproduction of ancestral humans, we can then design experiments to determine whether humans in fact possess an innate, cognitive ability to detect and avoid these animals (more on how to do this below). A major lesson of evolutionary psychology is that if you want to understand the brain, look deeply at the environment of our ancestors as focused through the lens of reproduction. If the presumptions of evolutionary psychology are correct, the structure of our brains should closely reflect our ancestral reproductive ecology. Thus, evolutionary psychology provides a method for perceiving the functional organization of the brain by studying the world--currently a far more tractable problem than disentangling neural assemblages.

• Knowing how these areas work in relation to the environment and the culture in which the human organism finds itself are the other areas of research in which evolutionary psychology shows the greatest promise. These spheres of research aim at configuring behavior models based on primate studies, hunter-gatherer research, and anthropological evidence into the best possible problem-solving probabilities of our ancestral behavior patterns. It is from these studies that evolutionary psychologists build behavior probabilities into our modern cultures and show us why we do the things we do -- based on biology.

• The reason that evolutionary psychology is important is that, scientists and scholars alike are finally all collaborating together to form a consensus on how the human brain, and thus human emotions, have evolved. Once we know how such emotions as prejudice, hate, and anger evolved, we, as humans, can begin to change these negative behavior mechanisms.

• We do this by being self-aware of, then controlling, the emotions that flow from our brain. It is this self-awareness and self-control that makes us human.

• We are separated from the animal within us by our higher consciousness. We have demonstrated that we can control our emotions and thus change our external behavior patterns. But we all must acknowledge that we are still attached by the flesh to our primal past.

Premises THAT the species Homo sapiens evolved from our

primate ancestors, most likely the Old World Primates. (Africa).

• THAT our ancestors formed social groups for protection, food gathering, and mating opportunities. Before plant and animal domestication, these groups were called hunter-gatherers.

• THAT the forming of these social groups created the need for group communication that evolved into behavioral mechanisms to communicate danger, food resources, mating signals, status, hunting, and defensive maneuvers.

• THAT long-term adaptation to environmental and cultural influences eventually became part of our genetic software. Language is a perfect example; all humans on the planet have the innate ability to learn a language.

• Listed in the next slide, in alphabetical order, are the behavioral traits that evolutionary psychologists, so far, have determined all humans on our planet share. Those with question marks are in the running to be considered as modules, but still raise question to their validity.

• Beauty Conception • Coalition Formation • Color Perception • Deception & Cheater Detection • Detecting Emotions • Face Recognition • Facial Symmetry Detection?• Food Aversions • Gender Identification?• Gossip • Humor • Incest Avoidance (Kin Recognition with Sexual Avoidance) • Infant Protectiveness? (obvious, our own children, (that's Parenting), but how about other infants outside

our family?).• Kin Recognition • Landscape Preferences • Language • Mate Preferences/Choice • Mental Maps • Object Recognition • Odor Avoidance (strong odor)• Parenting • Perception of Status/Ranking • Plant Spoilage (awareness of) • Romantic Love • Rough house play (in children) • Sexual Attraction • Sexual Orientation?• Sexual Avoidance • Self-Awareness • Social Group Reasoning

• Internal, personal, and interpersonal behavior is influenced by genetic codes, but not imprisoned by them. In our long evolutionary voyage, we have gone from total reflex action in the environment (nature) to understanding the cues from our kin and close companions as the basis for knowing the best course of action (nurture).

• In our modern world with vast communication networks in place, culture has the greatest influence. It is the dance between nature and nurture with nurture as the dominant leading partner that creates evolutionary psychology.

Evolution

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Transcript of Evolution