Essay about Evolution: Evolution and Natural Selection

Submitted By Lolahuynh1
Words: 773
Pages: 4
Open Document
Does evolution fashion perfect organisms?

The answer to this question, in a word, is no. There are at least four reasons why natural selection cannot breed perfection.
1. Organisms are locked into historical constraints. As we saw in Chapter 20, each species has a legacy of descent with modification from a long line of ancestral forms. Evolution does not scrap ancestral anatomy and build each new complex structure from scratch, but co-opts existing structures and adapts them to new situations. For example, the excruciating back problems some humans endure result in part because the skeleton and musculature modified from the anatomy of four-legged ancestors are not fully compatible with upright posture.
2. Adaptations are often compromises. Each organism must do many different things. A seal spends part of its time on rocks; it could probably walk better if it had legs instead of flippers, but it would not swim nearly as well. We humans owe much of our versatility and athleticism to our prehensile hands and flexible limb, which also make us prone to sprains, torn ligaments, and dislocations; structural reinforcement has been compromised for agility.
3. Not all evolution is adaptive. Chance probably affects the genetic structure of populations to a greater extent than was once believed. For instance, when a storm blows insects hundreds of miles over an ocean to an island, the wind does not necessarily pick up the specimens that are best suited to the new environment. And not all alleles fixed by genetic drift in the gene pool of the small founding population are better suited to the environment than alleles that are lost. Similarly, the bottleneck effect can cause nonadaptive or even maladaptive evolution.
4. Selection can only edit variations that exist. Natural selection favors only the most fit variations from what is available, which may not be the ideal traits. New alleles do not arise on demand.

With all these constraints, we cannot expect evolution to craft perfect organisms. Natural selection operates on a "better than" basis. We can see evidence for evolution in the subtle imperfections of the organisms it produces.

* * *

Natural selection is usually thought of as an agent of change, but it can also act to maintain the status quo. Stabilizing selection probably prevails most of the time, resisting change that may be maladaptive. Evolutionary spurts occur when a population is stressed by a change in the environment, migration to a new place, or a change in the genome. When challenged with a new set of problems, a population either adjusts through natural selection or becomes extinct. The fossil record indicates that extinction is the more common outcome. Those populations that do survive crises often change enough to become new species, as we will see in the next chapter.
REVIEW OF KEY CONCEPTS (with page numbers and key figures)

■ The modern evolutionary synthesis integrated Darwinism and Mendelism: science as a process (pp. 416-417)
■ The development of population genetics, with its emphases on quantitative inheritance and variation, brought
Show More

Related Documents: Essay about Evolution: Evolution and Natural Selection

Evolution: Evolution and Natural Selection Essay

Evolution Darwin's theory of evolution explains how species of living things have changed over geological time. The theory is supported by evidence from fossils, and by the rapid changes that can be seen to occur in microorganisms such as antibiotic-resistant bacteria. Many species have become extinct in the past, and the extinction of species continues to happen. Adaptations - cold climates Every organism has certain features or characteristics that allow it to live successfully in its habitat.…

Words 1505 - Pages 7

Evolution: Evolution and Natural Selection Essay

Once you’ve got life – how it evolves Modern systhesis – is called evolution. It means descent with modification. Homologous character or gene – acquired thru shared ancestory. Theory of natural selection – mechanismof adaptation and adaptive evlution. Evolution Descendants of ancestral forms Vertrebrates have common anscertor with something in the past It requires Variation in populations – can arise thru mutations in dna. Ie a point mutation – wher ea single base pair is changed which…

Words 691 - Pages 3

Essay on Evolution and Natural Selection

individuals contribute to the gene pool and because any given allele is present in very few individuals o Generally leads to loss of alleles and reduced genetic variability • Natural Selection: process by which such beneficial, heritable traits become more common in subsequent generations • Sexual Selection: a form of natural selection established by male competition for access to females and by the females choice of males • Sexual Dimorphism: differences in the size or appearance of males and females…

Words 5101 - Pages 21

Evolution By Natural Selection Is Wrong Essay

Evolution By Natural Selection Is Wrong!! All living things face many questions throughout their life such as what am I and what is the purpose on earth? Over the past centuries, science have been investigating these questions. At the same time, many cultures around the world have answers to these questions as well. According to science, these answers are concerned as myths or made up stories. Cultures all over the world believe “GOD” or “An Intelligent Designer” made all the living things. Modern…

Words 1609 - Pages 7

The Four Forces Of Evolution And Natural Selection

forces of evolution are mutation, gene flow, genetic drift, and natural selection. Mutation is a random change in a gene or chromosome, resulting in deletions, additions, or substitutions in the DNA sequence. Without mutation, there would be no evolution because the only way a sex cell can be passed down is through mutation. Gene flow is the exchange of genetic material between two populations. Genetic drift is the random change in allele frequency from one generation to the next. Finally, natural selection…

Words 412 - Pages 2

The Argument Between Evolution And Natural Selection

Evolution is such an important principle that must be understood. Of course there are always arguments between science and religion about the origin of man and how we have ended up where we are as a human race. More importantly, evolution is something that is explained and fully supported by scientists ever since its discovery. There are many parts to evolution than just physical differences in one species from different time periods. Something that has always interested me about evolution is specifically…

Words 731 - Pages 3

Essay on Anth: Evolution and Natural Selection

theories about natural selection has brought confusion to several scientists’ minds, debating whether these theories are true or not. As for Jonathan Weiner, he completely agrees with Darwin. In his article, Evolution in Action, he states how the biological life is quickly changing right in front of our eyes and claims that though there are arguments about whether Darwin’s theories are true or not, there has been evidence of natural selection. Weiner includes several examples of natural selection in his…

Words 492 - Pages 2

Human Influence On Sustainability, Evolution And Natural Selection

impact on sustainability, evolution, and natural selection. Here are some ways in which human activities can affect these processes. Habitat Destruction: Human activities such as deforestation and urbanization can result in the destruction of natural habitats. This can lead to the loss of biodiversity, which is crucial for the long-term sustainability of ecosystems. Species that are unable to adapt to these changes may face extinction, impacting both evolution and natural selection. 2. What is the difference…

Words 423 - Pages 2

Essay on Evolution: Natural Selection and Human Behavior

important contribution to human behavior. EP posits that behavior is produced by specialized cognitive modules that evolved through natural selection in response to specific adaptive problems faced by our hunter-gatherer ancestors. Many aspects of modern human behavior can be explained through an evolutionary perspective. For example, EP helps us understand sexual selection through its explanation of gender differences in attraction and mating relationships. Buss (1995) found that gender differences…

Words 670 - Pages 3

Evolution: Natural Selection and Beneficial Mutations Essay

The theory of evolution is one of the best-known scientific theories around. Evolution is fascinating because it attempts to answer one of the most basic human questions: Where did life, and human beings, come from? The theory of evolution proposes that life and humans arose through a natural process. The basic theory of evolution is surprisingly simple and has a few essential parts and stresses a purely naturalistic descent. That is, complex creatures evolve from more simplistic ancestors naturally…

Words 596 - Pages 3