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.

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  1. jedishrfu

    Biggest Breakthroughs in Biology and Neuroscience in 2023

    Covers: - An investigation of consciousness - Microbiomes evolve with us - How life keeps time
  2. sophiecentaur

    Innovative Evolution of the Bamboo-Eating Pandas: A Unique Survival Strategy

    Once you have got over the 'cute' appearance of pandas the temptation to regard them as a shouldn't be allowed, nonsense species. However, their evolution can actually be seen as a an inovative step towards. They have, apparently, been around for three million years so they are successful. You...
  3. K

    History - Evolution of ideas in the field of thermodynamics (statistics in mechanical and gas dynamics)

    Hi, I have a question regarding the evolution of idea in the field of thermodynamics. Boltzmann is genereally credited with the notion of stasticis and it's relation to entropy. However, Boltzmann was inspired by the work of Maxwell (who himself followed the conceptual models of Bernoullli for...
  4. hilbert2

    A Ground state calculation with a time averaged wave function

    An idea I was thinking about for the last few days: You want to calculate the ground state of some system from the Schrödinger eqn ##\hat{H}\left|\psi\right.\rangle = E\left|\psi\right.\rangle##. One way is to choose a trial state ##\left|\psi (t_0 )\right.\rangle## and use the TDSE to...
  5. uxioq99

    Exploring Solutions to Spin Evolution Equations

    By the statement of the question, a solution must take the form ##\begin{pmatrix} \Psi_1 \\ \Psi_2 \end{pmatrix}## and the energy operator will be as per usual ##\hat{E} = i\hbar \frac{\partial}{\partial t}##. I am confused by the fact that ##S_y = \frac{\hbar}{2} \begin{pmatrix} 0 & -i \\ i & 0...
  6. R

    I Understanding diagrams of the late stages of stellar evolution

    Hi, I have an upcoming exam in astrophysics. We have been told to make sure we study all figures and tables, s.t. we are able to explain them. However, I ran into these figures below, in my lecturer's PowerPoint and I do not know where they originate and aren't presented in my book. I'm having...
  7. jedishrfu

    Recent Article on the Evolution of a Theory of Covid Origins

  8. LittleSchwinger

    A Why Unitary Evolution? QM Justification Ideas

    The usual justification for why the evolution of physical systems is unitary in quantum mechanics involves arguments like "probabilities must sum to 1" or similar arguments that apply equally to any CPTP map. I'm just curious what justifications people here would use for selecting out unitary...
  9. H

    I Global evolution of a Bell pair of photons

    Hi Pfs, consider a pair of maximally entangled photons where the total momentum is null and the same thing for the total angular momentum. I suppose that this pair is like an universe: nothing outside the pair acts on it except maybe a device for the measurement of these two properties (no local...
  10. James1238765

    I Time evolution of the electromagnetic wavefunction on a lattice

    The Maxwell wavefunction of a photon is given in [here] as follows: Because the curl operation mixes 3 different components, this wavefunction only works for a minimum of 3 space dimensions, with each grid point having 6 component numbers ##{E^1, E^2, E^3, B^1, B^2, B^3}##, and with the...
  11. S

    I Deviations of conservation laws in cosmological evolution?

    If energy is "not conserved" in General Relativity (or at least, it is difficult to define it) in the context of an expanding accelerating spacetime (like it happens in our Universe), are there any observations of deviations from the strict conservation laws in the evolution and formation of...
  12. R

    On the origin and the evolution of information in the Universe

    [Mentor Note -- thread moved from the schoolwork forums to the technical forums] Homework Statement:: Tentative Note and summary on the origin and the evolution of information in the universe. Relevant Equations:: none As a teacher of physics I got many questions asked by my students when...
  13. Astronuc

    B Evolution of planetary system around a white dwarf

    An article came up on Phys.org about a white dwarf drawing in material from the planetary system surrounding it. Is this the ultimate fate of our solar system? https://phys.org/news/2022-06-dead-star-cannibalism-planetary-far-reaching.html...
  14. J

    Why do scientists call evolution a "theory"?

    Why do scientists refer to evolution as a theory which leads to the argument that evolution is "just a theory"? Why don't they use a less confusing word?
  15. BillTre

    Book Review: The Gene's-Eye View of Evolution

    The Gene's-Eye View of Evolution. New book by Arvid Ågren (2021), reviews the field of population genetics that is involved with selfish gene kind of thinking (The Selfish Gene, Dawkins, 1976). It breaks down the big arguments into smaller parts and analyses them. Lots of references, but not...
  16. Astronuc

    Formation and evolution of the Great Lakes in US/Canada border

    I was watching a program on the formation of the Great Lakes, and it is quite interesting and fascinating. The huge salt deposits under the Lakes Michigan, Huron and Erie and fossilized sea sponges provide evidence of a salt water sea in the past. Limestone formed from successive corral reefs...
  17. DennisN

    How did the alphabet evolve over time?

    One of my friends sent a link to this illustration which I found very, very fascinating: (Image by Matt Baker, UsefulChart.com, image source: link) If I decipher the chart correctly, e.g. the letter "O" developed from an image of an eye. According to the wiki page about "O" an eye indeed...
  18. A

    Why do we consider Neanderthals a different species than humans?

    According to wiki "Neanderthals are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago." But according to wiki again: "A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating...
  19. Lren Zvsm

    Sapient Life Indigenous to a Planet Orbiting a Red Dwarf

    I am considering writing a story that features aliens indigenous to a planet orbiting a red dwarf star. Even so, because of its proximity to the red dwarf, the planet's surface receives much more radiation than Earth's surface does. What is more, the planet has no moon to stabilize its...
  20. L

    Medical Evolution of people within a generation?

    Are there certain things that threaten human evolution or at least threaten to make us less functional as a species? If for example we started living twice as long due to medical intervention with better health and started having children at twice the average age? Would it hurt much to have...
  21. tworitdash

    A 2D space and 1D time evolution of a random field

    I want to develop a 2D random field and its change with time with constant velocity. My process: 1. Define a 2D grid [x, y] with n \times n points 2. Define 1D time axis [t] with n_t elements 3. Find the lagrangian distance between the points in space with the velocity in x and y ...
  22. D

    A What Does Constant Fidelity in Quantum States Imply?

    I have a fidelity between the initial state and final state is 1 at t=0,1,2...etc. What does it mean physically? Does it mean that the quantum state is not evolved here. But In quantum dynamics every physical system evolves with time.
  23. Viishnu

    Searching for a book like Evolution of Physics or Physics for the Inquiring Mind

    How did you find PF?: QuorA Can you please suggest me a book similar in content to evolution of physics or physics for the inquiring mind perhaps a book with more detail and scope but maintaining the clarity of content shown in the previous listed books above please reply if you know
  24. T

    Evolution and preservation of endangered animals

    Recently I saw a video from a Christian creationist who was trying to debunk evolution with an argument that if evolution gives us new species all the time why would we make an effort to preserve those that are going extinct. So I was thinking a little bit about it and these are my conclusions...
  25. D

    A How Does One Calculate the Time Evolution of a Photon in a Vacuum State?

    During time evolution of one photon with vacuum state with hamiltonian as a^†b+b^†a, the answer is cos(t/ℏ)|0,1⟩+isin(t/ℏ)|1,0⟩. But i don't know how to do calculation to get this answer. Can someone please help me? I tried to do this calculation: |0⟩|1⟩(t)=e−iHtℏ|0⟩|1⟩...
  26. M

    I ##\Lambda##CDM: Evolution of the population of galaxies

    The number of visible galaxies is to vanish in the long-term future with the ##\Lambda##CDM model (book and papers of L. Krauss et al). I am interested in a quantitative study on how the population of galaxies decreases; I could not find one so I do it myself: The scale factor...
  27. F

    Time evolution of a particle in momentum space

    Since it asks for the time evolution of the wavefunction in the momentum space, I write : ##\tilde{\Psi}(k,t) = < p|U(t,t_{0})|\Psi> = < U^\dagger(t,t_{0})p|\Psi>## Since ##U(t,t_{0})^\dagger = e^{\frac{i}{\hbar}\frac{\hat{p^2}t}{2m}}##, the above equation becomes ##\tilde{\Psi}(k,t) =...
  28. C

    Anti-oxidants, uric acid, and evolution

    This might be a 'that's just how it is' sort of question, but are there any theories of how humans and higher apes have evolved so that they don't break down uric acid? All other animals break this down into allantoin, and fish go one further and break that down into ammonia. Did 'us apes' end...
  29. stephen8686

    A Jaynes-Cummings Density Operator Evolution

    I am studying two level atoms interacting with fields in order to study Dicke Superradiance. From Loudon's book, the Optical Bloch Equations for a two level atom interacting with a field say (with rotating wave approx): $$\frac{d\rho_{22}}{dt}=- \frac{d\rho_{11}}{dt} = -\frac{1}{2}...
  30. jk22

    Medical Color of eyes : mutation due to evolution or racial selection?

    If different eyes appeared let say to less sun or an accidental mutation, has it become subject to selection of individuals like eugenism or due to modern gene technology nowadays ?
  31. Demystifier

    A Evolution of the Renner et al Wigner-like paradox

    In the first version of their arxiv preprint, Frauchiger and Renner argued that only the many word interpretation of QM was consistent. https://arxiv.org/abs/1604.07422v1 In the second version, the famous one published in Nature Communications, they radically changed their conclusions. They...
  32. Astronuc

    Billion-year-old fossil, a missing link in the evolution of animals?

    https://phys.org/news/2021-04-billion-year-old-fossil-reveals-link-evolution.html I used to have some literature on ancient single cell organisms, but I haven't seen it in decades. https://www.cell.com/current-biology/fulltext/S0960-9822(21)00424-3 Sediments of the Torridonian sequence of...
  33. K

    I Evolution of a Boltzman distribution

    Hello! Assume I have a classical system at a fixed temperature, such that the energy can be described by a Boltzmann distribution at that temperature. If I have a huge number of such systems in that state, and I measure the energy of each one, independently, the probability of measuring a given...
  34. pinball1970

    Human Brain Evolution: 2 Studies Examined

    Two studies on human brain evolution/development. FIRST A new study is the first to identify how human brains grow much larger, with three times as many neurons, compared with chimpanzee and gorilla brains. The study identified a key molecular switch that can make ape brain organoids grow more...
  35. CptXray

    I Coherent state evolution - nonlinear Hamiltonian

    Given the hamiltonian: \hat{H} = \hbar \omega_{0} \hat{a}^{+}\hat{a} + \chi (\hat{a}^{+}\hat{a})^2, where ##\hat{a}^{+}##, ##\hat{a}## are creation and annihilation operators. Find evolution of the state ##|\psi(t) \rangle##, knowing that initial state ##|\psi(0)\rangle = |\alpha\rangle##...
  36. Llukis

    I The time evolution of a Hamiltonian

    Dear everybody, Let me ask a question regarding the unitary time evolution of a given Hamiltonian. Let's start by considering a Hamiltonian of the form ##H(t) = H_0 + V(t)##. Then, I move to the interaction picture where the Schrödinger equation is written as $$ i\hbar \frac{d}{dt}...
  37. S

    I Are there other renowned physicists who believe in evolving laws of physics?

    The Canadian physicist, Lee Smolin proposed in the 90's that laws of nature may evolve and change over time. He begun proposing that only the constants of nature would evolve, while the most fundamental laws would remain the same, but recently he has change a little bit his ideas and has...
  38. LCSphysicist

    Modeling Quantum State Evolution with Schrodinger's Equation

    I am a little confused about how to solve it, probably it is easy but i didn't get it. I thought that would be a good idea to work with ##\psi = \alpha |a_{0}\rangle + \beta |a_{1}\rangle## in the Schrodinger equation with time involved, so that we get a system of differential equations...
  39. BillTre

    What Caused the Domestication of Dogs and Cats?

    New dog genomes from a variety of current dogs as well as many ancient dog genomes have recently revealed a lot about dog evolution. Article in Science (possibly pay-walled). News article in Science. NY Times article. Dog origins: It was thought that there might have been two origins of dogs...
  40. Someone_physics

    A Conditional time evolution entropy and the experimenter?

    Question --- So I've done a calculation which seems to suggest if I combine the system of a measuring apparatus to say an experimenter who "reacts" to the outcome of the the measurement versus one who does not. Then the change in entropy in both these situations is bounded by: $$ \Delta S_R...
  41. Nick tringali

    The Obstetrical Conundrum: Fontanelles & Human Birth Canals

    I want to do a project for my class on the obstetrical conundrum. Which is basically the antagonism of selective pressures on pelvic morphology. I need help to find literature. I want to know if over the course of history, if Human baby's fontanelles increased in size in order to compensate for...
  42. T

    B Question about the s-process and r-process in stellar evolution

    Hello I have been reading about the s-process and r-process in star evolution. And one thing i briefly saw mentioned was that both processes generally create higher abundances of elements with even number of protons than odd. It however did not explain why there is a slight bias towards even...
  43. C

    COVID The Evolution of the SARS-COV-2 virus

    The sudden appearance of SARS-COV-2 as a virulent pathogen in humans raises the question of how it gained the ability to attack human cells and why it is highly contagious. If I understand this right, an article in Virology Blog...
  44. A

    Evolution — information increase and entropy

    Not sure whether this is the right category but bear with me.I've seen graphics where the information increase with time of evolution is projected like the one in the link below from Carl Sagan's book https://www.researchgate.net/figure/Page-from-the-book-of-Carl-Sagan-21_fig2_322153131 Now I...
  45. J

    I Energy in the Hamiltonian formalism from phase space evolution

    The hamiltonian ´for a free falling body is $$H = \dfrac{p^2}{2m} + mgy$$ and since we are using cartesian coordinates that do not depend on time and the potential only depends on the position, we know that ##H=E##. For this hamiltonian, using the Hamilton's equations and initial conditions...
  46. Buzz Bloom

    Evolution of Hymen in Animals: Overview & Research

    I made an effort to find an answer to this question on the Internet, but I was unsuccessful. I did learn that there are some researchers who report that there are many living non-human animals with a hymen, but also that this may be controversial. In particular...
  47. S

    Binnig's fractal evolution applied to multiple universes?

    Gerd Binnig, Nobel laureate in physics in 1986, proposed in his article "The fractal structure of evolution" [1] that everything in the universe, including its laws, had changed and became what we have got today through a process which mixes some concepts from darwinian evolution and fractal...
  48. A

    Math-probability and theroy of evolution

    Why people believe that life become by accident if math say that it is almost imposible ? it is matahmaticly-statistic almost imposible that even simple protein become just by accident! mathematitions calculate that probability to becom simple protein by accident is only 1 : 10 to the 171...