What is Evolution: Definition and 731 Discussions

Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes that are passed on from parent to offspring during reproduction. Different characteristics tend to exist within any given population as a result of mutation, genetic recombination and other sources of genetic variation. Evolution occurs when evolutionary processes such as natural selection (including sexual selection) and genetic drift act on this variation, resulting in certain characteristics becoming more common or rare within a population. It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms and molecules.The scientific theory of evolution by natural selection was conceived independently by Charles Darwin and Alfred Russel Wallace in the mid-19th century and was set out in detail in Darwin's book On the Origin of Species. Evolution by natural selection was first demonstrated by the observation that more offspring are often produced than can possibly survive. This is followed by three observable facts about living organisms: (1) traits vary among individuals with respect to their morphology, physiology and behaviour (phenotypic variation), (2) different traits confer different rates of survival and reproduction (differential fitness) and (3) traits can be passed from generation to generation (heritability of fitness). Thus, in successive generations members of a population are more likely to be replaced by the progenies of parents with favourable characteristics that have enabled them to survive and reproduce in their respective environments. In the early 20th century, other competing ideas of evolution such as mutationism and orthogenesis were refuted as the modern synthesis reconciled Darwinian evolution with classical genetics, which established adaptive evolution as being caused by natural selection acting on Mendelian genetic variation.All life on Earth shares a last universal common ancestor (LUCA) that lived approximately 3.5–3.8 billion years ago. The fossil record includes a progression from early biogenic graphite, to microbial mat fossils, to fossilised multicellular organisms. Existing patterns of biodiversity have been shaped by repeated formations of new species (speciation), changes within species (anagenesis) and loss of species (extinction) throughout the evolutionary history of life on Earth. Morphological and biochemical traits are more similar among species that share a more recent common ancestor, and can be used to reconstruct phylogenetic trees.Evolutionary biologists have continued to study various aspects of evolution by forming and testing hypotheses as well as constructing theories based on evidence from the field or laboratory and on data generated by the methods of mathematical and theoretical biology. Their discoveries have influenced not just the development of biology but numerous other scientific and industrial fields, including agriculture, medicine and computer science.

View More On Wikipedia.org
Recent contents Top users
  1. S

    I What is "unitary evolution" of something in physics?

    What do we mean when we say that a system can't change (in time) because its evolution is unitary?
  2. 1oldman2

    What can the evolution of the ribosome tell us about the origin of translation?

    https://www.newscientist.com/article/mg23631500-500-the-very-first-living-thing-is-still-alive-inside-each-one-of-us/ "We can stop <<profanity deleted>> about the origin of life," says Loren Williams, a biochemist at the Georgia Institute of Technology in Atlanta. "We can see it."
  3. Anupama

    Linearity of time evolution in classical mechanics

    I came to know that time evolution in classical mechanics is highly non linear. Is there any case that it become linear?
  4. I

    Time evolution of quantum state with time ind Hamiltonian

    Homework Statement Part e) Homework Equations I know that the time evolution of a system is governed by a complex exponential of the hamiltonian: |psi(t)> = Exp(-iHt) |psi(0)> I know that |psi(0)> = (0, -2/Δ) The Attempt at a Solution I'm stuck on part e. I was told by my professor...
  5. C

    I Solving LO DGLAP Evolution: Defining F and Physical Meaning

    Consider the leading-order (LO) DGLAP ((Dokshitzer–Gribov–Lipatov–Altarelli–Parisi) equation $$x \mu^2 \frac{d xg(x,\mu^2)}{d\mu^2}= \alpha_s \int_x^1 dz P_{gg}(z) \frac{x}{z} g(\frac{x}{z}, \mu^2) + \dots\,\,\,\,\,\,\,\,\,\,\,\,\,(1) $$ Define an unintegrated parton density function (PDF) by...
  6. M

    Light and oxygen acting upon the eye and the lung during the process of Evolution

    Did the evolution of the eye include interaction/reaction with a specific frequency of light? Did the evolution of the lung include interaction/reaction with the air density, humidity, and temperature of its environment?
  7. F

    Life on other planets, are we looking at the wrong planets?

    Scientists are looking for Earth like planets/bodies to find life on other planets/bodies, somewhere that is warm enough that liquid water can exist, and somewhere with basic organic molecules. Here's where I have a concern, in the 4 billion years of Earth's life, to our knowledge life had only...
  8. tom.stoer

    A Algebraic structure in time evolution

    In quantum mechanics time evolution is defined via a unitary operator $$U(t^\prime,t) = e^{-iH(t^\prime-t)}$$ Now let's forget about the fact that we know this exponential representation and that we know that the U's fulfill the group axioms, i.e. that we can multiply any two U's, regardless...
  9. Monci

    Quantum physics time evolution of an overlap

    Homework Statement [/B] I'm trying to solve the following problem. (a) was easy but I am stuck at (b). Homework Equations [/B] Since we are told that the Hamiltonian is conserved, and the answer is in terms of the uncertainty of H, I assume I have to use the conservation of uncertainty...
  10. omnipojack

    Writing: Input Wanted "Natural Born" Androids/Cyborgs

    At the time my story takes place, humans are in an evolutionary transition period. They have been able to modify DNA/genes so that people can have accessories, so to speak (communicator built into your arm, infrared sight, joints that can sustain falls from great heights, etc.), but very few...
  11. ORF

    Biology: Evolution: General selection rules?

    Hello In evolution, the archetype rule is the "natural selection" rule. Are the other selection rules? (technological selection rules, cultural rules, etc) Thank you for your time. Regards, ORF
  12. BillTre

    Chromosome and Large Scale Genome Evolution

    As a kind of off-thread elaboration on a thread on protein evolution, here is a Science news article on the evolution of mammalian chromosomes. By using full genome sequences, they are trying to trace back the evolution of mammalian genomes to their ancestral set of chromosomes. They only...
  13. redtree

    I Green's function and the evolution operator

    The Green's function is defined as follows, where ##\hat{L}_{\textbf{r}}## is a differential operator: \begin{equation} \begin{split} \hat{L}_{\textbf{r}} \hat{G}(\textbf{r},\textbf{r}_0)&=\delta(\textbf{r}-\textbf{r}_0) \end{split} \end{equation}However, I have seen the following...
  14. A

    B Wave-particle-duality and the evolution of the universe

    If I've understood correct, every particle in the universe exists in a waveform, which I've understood to mean propability where the particle does exist? Then which I've understood is, that the wave transforms into a particle only when observed, is this correct? Then if it is correct, how...
  15. M

    What are the Benefits of a Holistic Approach in Science?

    Hi, my Name is Markus and I'm from Germany, I have more a lingustic & IT background with basics in physics from school times (some years ago, I have to say). I have a couple of more holistic questions, hope that is ok, please let me know, Have a great day!
  16. Dyatlov

    I Inequality for the time evolution of an overlap

    Hello. I am trying to prove that the uncertainty in energy for a normalized state limits the speed at which the state can become orthogonal to itself. The problem is number 2 on https://ocw.mit.edu/courses/physics/8-05-quantum-physics-ii-fall-2013/assignments/MIT8_05F13_ps6.pdf Having issues...
  17. BillTre

    The Origin of People -- hominin migration and evolution

    Origins of various modern human populations has been the subject of a few posts recently. Below is a link to a Science mag news article on this subject. Modern Archeology has been using new tools, such as DNA analysis (of modern populations and ancient dead people) and isotope analysis (on dead...
  18. T

    Why arthropod has not evolved to be huge?

    Q: Why arthropods have not evolved to be huge? 1. Homework Statement Arthropods have not been able to achieve great size because (1) the type of organ systems they possesses could not support·such a development (2) they would be unable to successfully reproduce (3) chitin is brittle and must be...
  19. D

    How Does an Extra Factor of i Affect Quantum Probability Calculations?

    Homework Statement I am not sure about (c) and (d). Firstly, I calculated the eigenvector of A : |v_1> = ( |2 > - |1> )/ √(2) ,eigenvalue -2 |v_2> = ( |2> + |1>) / √(2) , eigenvalue 2 For (c), basically it follows from part (b) where the probability of a_1 is given by the formula | <v_1 | ψ...
  20. *now*

    Meaning = Information + Evolution

    This paper offers a "first link of a chain", bridging physical and, psychological or linguistically, mental notions of meaningful information. https://arxiv.org/pdf/1611.02420.pdf Meaning = Information + Evolution Carlo Rovelli CPT, Aix-Marseille Universit ́e, Universit ́e de Toulon, CNRS...
  21. durant35

    I Many worlds and cosmological evolution

    Hello guys, I have a question that came up to my mind while thinking about the evolution of our universe and quantum mechanics. It involves cosmology so maybe that was the right spot to post it, and of course the moderators can do it if they feel it's more adequate for the thread, but my...
  22. D

    QM: The time evolution of a Gaussian wave function

    Heads up, I only recently got into quantum mechanics and don't feel like I got a solid grasp on the material yet. 1. Homework Statement Given is the wave function of a free particle in one dimension: \begin{equation} \psi(x,0) = \left( \frac{2}{\pi a^2} \right)^{1/4} e^{i k_0 x} e^{-x^2/a^2}...
  23. mohau tshekoeng

    B What are the chances of evolution of organisms in space

    Will it be possible for an organism to evolve in order to adapt to conditions at space?
  24. Cal ben

    How is speciation possible within known confines?

    Please someone help me understand the concept of the actual occurrence of speciation. Cataclysmic Evolution may account for some species but not many, it could only practically apply to asexual species and would undermine genetic diversity. Actually I can save a lot of explanation by clarifying...
  25. B

    Time Evolution After Sudden Potential Change

    Homework Statement A particle in an infinite potential well ##V(x) = 0, -\frac{a}{2} \leq x \leq \frac{a}{2}##, and infinite elsewhere is in it's ground state. Subsequently, the potential is removed and the particle is free to move. How does the probability distribution in x and p change...
  26. Singlau

    B On the post-main-sequence evolution

    The path on an HR diagram after a star leaves the main sequence stage is known as post-main sequence evolution. In the graph, it consists of 2 parts: sub-giant branch and red giant branch. The near-horizontal is the former one, and the near-vertical is the latter one. Subgiants are...
  27. Jorrie

    I Evolution of the Energy Density Parameters

    I am busy with an effort to show how the energy density parameters evolve over time in an update of the LightCone7 calculator. See the posts on the thread Steps on the way to Lightcone cosmological calculator. As part of this effort, I ran into some difficulties with deciding how to find and...
  28. garylau

    Did this guy state something wrong about evolution theory?

    i have found one article state something like this:"""Any real evolution (macroevolution) requires an expansion of the gene pool, the addition of new genes (genons) with new information for new traits as life is supposed to move from simple beginnings to ever more varied and complex forms...
  29. G

    B Evolution of Principles: Michelson-Morley, Lorentz & Einstein

    Hi forum, I followed through Feynamn's derivation to show the different times taken for light by the parallel and perpendicular paths of the Michelson Morley apparatus. He showed that it took longer for light to go to the far mirror and back if it were parallel to the direction the whole...
  30. Ygggdrasil

    New Findings about the Evolution of Complex Cellular Life

    Humans, other animals, plants, fungi and almost all other forms of complex, multi-cellular life are known as eukaryotes. How eukaryotes evolved from simpler prokaryotic organisms is a major question in evolutionary biology. The current view is that eukaryotes evolved from the fusion between a...
  31. newjerseyrunner

    What's the purpose of genders in evolution

    I'm working on an experiment where I mimic biological evolution. I'm doing sexual reproduction to allow gene swapping because I see it as beneficial in terms of evolution. I got to wondering if I should include genders in my simulation. What is the evolutionary reason for only allowing half...
  32. K. Doc Holiday

    B Questions about the origin and evolution of dark energy.

    Dark Energy; origin and evolution I have read the threads but I still have some unanswered questions about the origin and evolution of dark energy. Has dark energy existed since the big bang? If so, why did it remain dormant for billions of years. Or did it spontaneously jump into existence...
  33. jamalkoiyess

    Stellar Evolution: In-Depth Books for Learners

    hello PF, I want to know more about stellar evolution and about the end of the star's life. I want something that is not very superficial as i get bored when the content is not really deep. Thanks.
  34. S

    What is the Origin of Eukarya and Its Relationship to Bacteria and Archaea?

    I'm wondering if the issue of bacteria and archaea having a single last universal common ancestor (LUCA) with eukarya diverging later, or all three having distinct common ancestors, has been clarified. I've seen a number of texts indicating the eukarya diverged much later, but also some...
  35. A

    Difficulty understanding evolution

    Hi I am and athiest and I believe on evolution, but there is an aspect of it that I can't get to grips with. We know evolution doesn't have a conscious mind and that it is the natural blind process of survival of the fittest, based on mutations over generations that are useful to the species...
  36. L

    Detailed list of all known human ancestors

    Hi everyone, In Carl Sagan's Cosmos there's a short animation video illustrating the shape of all human ancestors, starting from single cell organisms, morphing towards the modern humans. I've searched for a complete list of known human ancestors like that one, but I couldn't find anything like...
  37. R

    If evolution is true then why there is a monkey until this moment

    it is a common arrangement that say if evolution is true then why there is a monkey until this moment . I now that evolution is correct but who i can answer this question .
  38. Milsomonk

    Time evolution of a two-state system

    Homework Statement Hey guys, I have a question that asks; Assume an Electron Nuetrino (U1) is produced at t = 0. Find the state U(t) for later times t > 0. To give some context the question is based on a two state system where U1 = Collumn vector (sin(theta) cos(theta)) and U2...
  39. S

    Finding the State and Expectation Value for a Free Particle at Time t

    Homework Statement The eigenstates of the momentum operator with eigenvalue k are denoted by |k>, and the state of the system at t = 0 is given by the vector |{ψ}>=\int \frac {dk}{2π} g(k)|{k}> Find the state of the system at t, |ψ(t)>. Compute the expectation value of \hat{P}. Homework...
  40. H

    Sealed tank pressure evolution

    Hi all, I have some troubles with some basics thermodynamic rules. I have a sealed tank filled with fuel at Patm and at a temperature T. In this tank after filling, is composed of 3/4 liquid and 1/4 gas. I was wondering how the pressure inside the tank will change if we change the boundaries...
  41. Radu Mitroi

    B What percentage of the universe do we know

    Hello. First of all, I must say that I'm new to this forum, so I apologize if I'm posting in the wrong section. I'm a 17 year old with not that much knowledge about physics, so if what I'm talking about makes no sense or is completely stupid, just let me know. A couple of days ago I asked...
  42. M

    How does evolution theory fit the entropy theory

    the second law of thermodynamic state that their will be more chaos, and natural selection in the opposite of that. maybe this is a stupid question but can somebody anser this
  43. G

    A Black Hole information paradox and evolution in time

    I refer to a Schwarzschild Black Hole as the simplest example, and a well defined time outside the hole, say the Schwarzschild time. The information paradox of BH deals with the question of what stuff has fallen into the hole, but I am not aware that it deals with the question when the...
  44. K

    I About the time evolution of a wave packet

    In some texts of fundamental quantum mechanics, it introduces the wave packet by Fourier transformation of a momentum wave into a spatial version. This is easy to understand because, analogy to the optical wave, a typical beam could compose waves of more than one frequencies. The general form is...
  45. S

    Nausea from vertigo: an evolutionary by-product?

    Why do humans (and other mammals) get nauseated from dizziness or vertigo? I can see the evolutionary advantage of nausea from food poisoning, but I can't see the direct "link" between vertigo and vomit. I found something on verywell.com...
  46. F

    Quantum well, time evolution of probabilities

    hey, this thread might be a bit longer, but I have already calculated everything and I am quiet sure that it is right :) Just need someone who confirms me or not :) 1. Homework Statement Time evolution of probabilities. An electron inside a quantum well of length L is at time t = 0 in the...
  47. DaveC426913

    Gaining Insight into Evolution and Natural Selection

    I have read some amount of literature on evolution and natural selection over the years and, while I certainly learn a lot, it never seems to quite help me grok the breadth of change over deep time. So I have some rather naive thoughts that I'll phrase in the form of incredulity. They are...
  48. davenn

    Wednesday giggle - the origin of Evolution

  49. J

    A Unitary evolution while rapid change of potential?

    Imagine potential well which in t=0 switches to a different potential well (instantly), like in the picture below. So in negative times the wavefunction density should tend to be localized in the first well, in positive times to be localized in the second well...
  50. S

    I Time evolution after "turning off" square well

    How how can we calculate the future evolution of a particle after the infinite square well potential is (somehow) turned off, releasing it into a free state? Assuming that it was in the ground state before.
Back
Top