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Evolution explains the origin of life

It is a common misunderstanding that evolution includes an explanation of life’s origins. Conversely, some of the theory’s critics believe that it cannot explain the origin of life. The theory does not try to explain the origin of life. The theory of evolution explains how populations change over time and how life diversifies the origin of species. It does not shed light on the beginnings of life including the origins of the first cells, which is how life is defined. The mechanisms of the origin of life on Earth are a particularly difficult problem because it occurred a very long time ago, and presumably it just occurred once. Importantly, biologists believe that the presence of life on Earth precludes the possibility that the events that led to life on Earth can be repeated because the intermediate stages would immediately become food for existing living things.

However, once a mechanism of inheritance was in place in the form of a molecule like DNA either within a cell or pre-cell, these entities would be subject to the principle of natural selection. More effective reproducers would increase in frequency at the expense of inefficient reproducers. So while evolution does not explain the origin of life, it may have something to say about some of the processes operating once pre-living entities acquired certain properties.

Organisms evolve on purpose

Statements such as “organisms evolve in response to a change in an environment” are quite common, but such statements can lead to two types of misunderstandings. First, the statement must not be understood to mean that individual organisms evolve. The statement is shorthand for “a population evolves in response to a changing environment.” However, a second misunderstanding may arise by interpreting the statement to mean that the evolution is somehow intentional. A changed environment results in some individuals in the population, those with particular phenotypes, benefiting and therefore producing proportionately more offspring than other phenotypes. This results in change in the population if the characteristics are genetically determined.

It is also important to understand that the variation that natural selection works on is already in a population and does not arise in response to an environmental change. For example, applying antibiotics to a population of bacteria will, over time, select a population of bacteria that are resistant to antibiotics. The resistance, which is caused by a gene, did not arise by mutation because of the application of the antibiotic. The gene for resistance was already present in the gene pool of the bacteria, likely at a low frequency. The antibiotic, which kills the bacterial cells without the resistance gene, strongly selects individuals that are resistant, since these would be the only ones that survived and divided. Experiments have demonstrated that mutations for antibiotic resistance do not arise as a result of antibiotic.

In a larger sense, evolution is not goal directed. Species do not become “better” over time; they simply track their changing environment with adaptations that maximize their reproduction in a particular environment at a particular time. Evolution has no goal of making faster, bigger, more complex, or even smarter species, despite the commonness of this kind of language in popular discourse. What characteristics evolve in a species are a function of the variation present and the environment, both of which are constantly changing in a non-directional way. What trait is fit in one environment at one time may well be fatal at some point in the future. This holds equally well for a species of insect as it does the human species.

Section summary

Evolution is the process of adaptation through mutation which allows more desirable characteristics to be passed to the next generation. Over time, organisms evolve more characteristics that are beneficial to their survival. For living organisms to adapt and change to environmental pressures, genetic variation must be present. With genetic variation, individuals have differences in form and function that allow some to survive certain conditions better than others. These organisms pass their favorable traits to their offspring. Eventually, environments change, and what was once a desirable, advantageous trait may become an undesirable trait and organisms may further evolve. Evolution may be convergent with similar traits evolving in multiple species or divergent with diverse traits evolving in multiple species that came from a common ancestor. Evidence of evolution can be observed by means of DNA code and the fossil record, and also by the existence of homologous and vestigial structures.

Questions & Answers

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Sitali
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Memiru
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Rorisang
what is meant by submicroscopic?
anji Reply
what is the meaning of biology
Dorathy Reply
biology is scientific study of living things
GUYO
what is chromosomes?
Mabiya Reply
it is a cell structure that contains DNA histones protein and other structural proteins
Ekechi
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Kashah
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Hassan Reply
liver is an organ in the body that meterbolise nutrients and produce bile.
Ekechi
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Gulfam
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Kashah
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Eric Reply
Biology is you
muayad
Biology is the natural science that studies life and living organisms, including their physical structure, chemical processes, molecular interactions, physiological mechanisms, development and. evolution
Suzette
biology is the study of living things and none living things
Ekechi
study of living organisms
anji
The mamalian endoskeleton has 206 bones
kaazim Reply
hii
Hannah
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Suzette
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Hannah
good thanks
Suzette
have you done the actual course?
Suzette
How many bones do human body have?
moses Reply
I don't know please help me
Kisito
206
Waneh
206
Moses
206
anji
what are these geneti materials
ONELIA Reply
Name five parts of female reproductive system and state the function of each part
Angel Reply
What is biology
Angel
What is biology
Angel
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ketchem
Ok
Angel
Name five parts of female reproductive system and state the function of each part
Angel
What is the meaning of respiration
Idriss Reply
the act or process of breathing .
Suzette
the process is very long as I know
Idriss
do you want more details ?
Suzette
yes offcourse
Smiso
what does the term diploid and haploid mean?
ONELIA
what is virgina
Shebas Reply
A female reproductive organs
Julius
fuvu LA binadam linamifupa mingapi?
Hamis Reply
explain dicot n monocot plant
Henry Reply
Di= 2cotiledon mono=cotiledon
muayad
Mono = 1 cotiledon
muayad
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Shebas
A Virginia is a part of a female ,the passage of a child during child birth, receiver of the penis and the passage of menstral flow
Idriss
what is biology
Hassan Reply
what is liver
Hassan
Biology is the study of living organisms
Gifty
is the study of life of living organisms
Chansa
study all about organisms like their reproduction, evolution , behaviour Physiology, etc
Ubaid
this is what we call "life"@
Chansa
is the study of living organisms on earth
okubasu
It is the study of living organism
Idriss
Biology is the study of all living organisms
ketchem
what is copulation
ketchem

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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