ZME Science
The human brain did not evolve to wake up with an alarm clock, check strangers’ achievements on social media, learn about the latest global disaster and calculate its social worth before breakfast. Every single day. Yet for many people, that is modern life. A new scientific review argues that stress, loneliness, status anxiety, the fear of falling behind, and all the other angst typical of modern life may be partly understood as “evolutionary mismatch”……Continue reading….
By: Tibi Puiu
Source: ZME Science
.
Critics:
Evolutionary mismatch (also “mismatch theory” or “evolutionary trap”) is the evolutionary biology concept that a previously advantageous trait may become maladaptive due to change in the environment, especially when change is rapid. It is said this takes place in animals. This phenomenon occurs as a result of a species’ environment and society changing faster than its biology, causing them to not be able to adapt to the modern world.
Environmental change leading to evolutionary mismatch can be broken down into two major categories: temporal (change of the existing environment over time, e.g. a climate change) or spatial (placing organisms into a new environment, e.g. a population migrating). Since environmental change occurs naturally and constantly, there will certainly be examples of evolutionary mismatch over time. However, because large-scale natural environmental change – like a natural disaster – is often rare, it is less often observed.
Another more prevalent kind of environmental change is anthropogenic (human-caused). In recent times, humans have had a large, rapid, and trackable impact on the environment, thus creating scenarios where it is easier to observe evolutionary mismatch.Because of the mechanism of evolution by natural selection, the environment (“nature”) determines (“selects”) which traits will persist in a population.
Therefore, there will be a gradual weeding out of disadvantageous traits over several generations as the population becomes more adapted to its environment. Any significant change in a population’s traits that cannot be attributed to other factors (such as genetic drift and mutation) will be responsive to a change in that population’s environment; in other words, natural selection is inherently reactive. Shortly following an environmental change, traits that evolved in the previous environment, whether they were advantageous or neutral, are persistent for several generations in the new environment.
Because evolution is gradual and environmental changes often occur very quickly on a geological scale, there is always a period of “catching-up” as the population evolves to become adapted to the environment. It is this temporary period of “disequilibrium” that is referred to as mismatch. Mismatched traits are ultimately addressed in one of several possible ways: the organism may evolve such that the maladaptive trait is no longer expressed, the organism may decline and/or become extinct as a result of the disadvantageous trait, or the environment may change such that the trait is no longer selected against.
The Neolithic Revolution brought about significant evolutionary changes in humans; namely the transition from a hunter-gatherer lifestyle, in which humans foraged for food, to an agricultural lifestyle. This change occurred approximately 10,000–12,000 years ago. Humans began to domesticate both plants and animals, allowing for the maintenance of constant food resources. This transition quickly and dramatically changed the way that humans interact with the environment, with societies taking up practices of farming and animal husbandry.
However, human bodies had evolved to be adapted to their previous foraging lifestyle. The slow pace of evolution in comparison with the very fast pace of human advancement allowed for the persistence of these adaptations in an environment where they are no longer necessary. In some human societies that now function in a vastly different way from the hunter-gatherer lifestyle, these outdated adaptations now lead to the presence of maladaptive, or mismatched, traits.Behavioral examples of evolutionary mismatch theory include the abuse of dopaminergic pathways and the reward system.
An action or behavior that stimulates the release of dopamine, a neurotransmitter known for generating a sense of pleasure, will likely be repeated since the brain is programmed to continually seek such pleasure. In hunter-gatherer societies, this reward system was beneficial for survival and reproductive success. But now, when there are fewer challenges to survival and reproducing, certain activities in the present environment (gambling, drug use, eating) exploit this system, leading to addictive behaviors.
Examples of evolutionary mismatch also occur in the modern workplace. Unlike our hunter-gatherer ancestors who lived in small egalitarian societies, the modern work place is large, complex, and hierarchical. Humans spend significant amounts of time interacting with strangers in conditions that are very different from those of our ancestral past. Hunter-gatherers do not separate work from their private lives, they have no bosses to be accountable to, or no deadlines to adhere to.
Our stress system reacts to immediate threats and opportunities. The modern workplace exploits evolved psychological mechanisms that are aimed at immediate survival or longer-term reproduction. These basic instincts misfire in the modern workplace, causing conflicts at work, burnout, job alienation and poor management practices.
Herbivores have created selective pressure for plants to possess specific molecules that deter plant consumption, such as nicotine, morphine, and cocaine. Plant-based drugs, however, have reinforcing and rewarding effects on the human neurological system, suggesting a “paradox of drug reward” in humans. Human behavioral evolutionary mismatch explains the contradiction between plant evolution and human drug use. In the last 10,000 years, humans found the dopaminergic system, or reward system, particularly useful in optimizing Darwinian fitness.
While drug use has been a common characteristic of past human populations, drug use involving potent substances and diverse intake methods is a relatively contemporary feature of society. Human ancestors lived in an environment that lacked drug use of this nature, so the reward system was primarily used in maximizing survival and reproductive success. In contrast, present-day humans live in a world where the current nature of drugs render the reward system maladaptive.
This class of drugs falsely triggers a fitness benefit in the reward system, leaving people susceptible to drug addiction. The modern-day dopaminergic system presents vulnerabilities to the difference in accessibility and social perception of drugs.
No comments:
Post a Comment