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Evolution Explained: The Beginning & Development of Life

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Evolutionary Processes & Mechanisms

101 Reasons Why Evolution is True | Common descent. In evolutionary biology, a group of organisms share common descent if they have a common ancestor. There is strong evidence that all living organisms on Earth are descended from a common ancestor, called the last universal ancestor or LUA (or last universal common ancestor, LUCA).[1][2] Common ancestry between organisms of different species arises during speciation, in which new species are established from a single ancestral population.

Organisms which share a more recent common ancestor are more closely related. Universal common descent through an evolutionary process, that there was only one progenitor for all life forms, was first proposed by Charles Darwin in On the Origin of Species, which ended with "There is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one".[8] The theory has been recently popularized by Richard Dawkins, in The Ancestor's Tale, and others. History[edit] Evidence of universal common descent[edit]

Evidence of common descent. Evidence of common descent of living things has been discovered by scientists working in a variety of fields over many years. This evidence has demonstrated and verified the occurrence of evolution and provided a wealth of information on the natural processes by which the variety and diversity of life on Earth developed. This evidence supports the modern evolutionary synthesis, the current scientific theory that explains how and why life changes over time.

Evolutionary biologists document evidence of common descent: making testable predictions, testing hypotheses, and developing theories that illustrate and describe its causes. Fossils are important for estimating when various lineages developed in geologic time. As fossilization is an uncommon occurrence, usually requiring hard body parts and death near a site where sediments are being deposited, the fossil record only provides sparse and intermittent information about the evolution of life.

Genetics[edit] DNA sequencing[edit] Last universal ancestor. A cladogram linking all major groups of living organisms to the LUA (the black trunk at the bottom). This graph is derived from ribosomal RNA sequence data.[1] A cladogram linking all major groups of living organisms to the LUA (short trunk at the center). This graph is derived from complete genome sequencing data. The last universal ancestor (LUA), also called the last universal common ancestor (LUCA), cenancestor, or progenote, is the most recent organism from which all organisms now living on Earth descend.[2] Thus it is the most recent common ancestor (MRCA) of all current life on Earth.

The LUA is estimated to have lived some 3.5 to 3.8 billion years ago (sometime in the Paleoarchean era).[3][4] The earliest evidences for life on Earth are graphite found to be biogenic in 3.7 billion-year-old metasedimentary rocks discovered in Western Greenland[5] and microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia.[6][7] Features[edit] Hypotheses[edit] Most recent common ancestor. In genetics, the most recent common ancestor (MRCA) of any set of organisms is the most recent individual from which all organisms in a group are directly descended. The term is often applied to human genealogy. The MRCA of a set of individuals can sometimes be determined by referring to an established pedigree. However, in general, it is impossible to identify the specific MRCA of a large set of individuals, but an estimate of the time at which the MRCA lived can often be given. Such time to MRCA (TMRCA) estimates can be given based on DNA test results and established mutation rates as practiced in genetic genealogy, or by reference to a non-genetic, mathematical model or computer simulation.

The term MRCA is usually used to describe a common ancestor of individuals within a species. It can also be used to describe a common ancestor between species. The term MRCA may also be used to identify a common ancestor between a set of organisms via specific gene pathways. The Genius of Charles Darwin. Darwin. Happiest at home with his notebooks and his microscope, he shunned the public eye. Controversy made him ill. This brilliant observer of nature kept his most original and revolutionary idea under wraps for decades. Yet today, two centuries after Charles Darwin's birth, nearly everyone knows his name.

What did Darwin do, and why does he still matter so much? Keenly observing nature in all its forms--from fossil sloths to mockingbirds, primroses to children--Darwin saw that we all are related. Every living thing shares an ancestry, he concluded, and the vast diversity of life on Earth results from processes at work over millions of years and still at work today. Darwin's explanation for this great unfolding of life through time--the theory of evolution by natural selection--transformed our understanding of the living world, much as the ideas of Galileo, Newton, and Einstein revolutionized our understanding of the physical universe. Charles Darwin looked closely at life. Evolution Library: Evidence for Evolution. Peabody Museum - Tree of Life.

Learn about the Tree of Life! Pick a topic to learn about, or press the "Next Section" button below to go in order: What is the Tree of Life? What is a Phylogenetic Relationship? Evolution Along the Branches Extreme Divergence! Convergent Evolution Convergent Insect Eaters A Succulent Convergence Big Surprises in the Tree of Life Elephant Shrews Afrotheria - Elephants, Elephant Shrews, and More! A Monumental Scientific Challenge Computational Complexity Why Study the Tree of Life? Phylogenetic Predictions.

Understanding Evolution. The bacteria that changed the world - May, 2017 The make-up of Earth's atmosphere, once the domain of Earth science textbooks, has become an increasingly "hot" news topic in recent decades, as we struggle to curb global warming by limiting the carbon dioxide that human activity produces. While the changes that humanity has wrought on the planet are dramatic, this isn’t the first time that one species has changed Earth’s atmosphere. Three billion years ago, there was no free oxygen in the atmosphere at all. Life was anaerobic, meaning that it did not need oxygen to live and grow. That all changed due to the evolution of Cyanobacteria, a group of single-celled, blue-green bacteria.

Read the rest of the story here | See the Evo in the News archive. GEOL 104: The Colonization of Land and Life on Land Before the Dinosaurs. Fall Semester 2013The Colonization of Land and Life on Land Before the Dinosaurs I. The Colonization of Land Life on Earth first evolved in the seas over 3.5 billion years ago, and even today the majority of living things are aquatic. The terrestrial realm of land and air offers many challenges to organisms adapted to aquatic life: Gravity: aquatic life is buoyed by water. The first organisms that spent at least sometime out of water were algae mats along the edges of seas and lakes (which are among the oldest fossils known!)

Among the first fully terrestrial organisms were true primitive plants that had colonized land by the Silurian Period (443.4-419.2 Ma). The first terrestrial animals were various types of arthropods (bugs, broadly defined): the ancestors of millipedes and centipedes, the earliest arachnids, and the ancestors of insects were established on land in the Silurian Period. (Other groups, such as earthworms, other worms, snails, and so on colonized during this time.) II. GEOL 104: Systematics. Fall Semester 2013Systematics I. The Tree of Life The most important pattern: the Tree of Life.

Darwin and Wallace demonstrated the reality of Divergence through Time and Common Ancestry: Divergence from common ancestors Two (or more) distinct variations in an ancestral population convey their own advantage against the rest of the population Over time, these two (or more) variations will become more distinct from each other If they diverge enough, they will no longer be able to mate with each other: will be different species Divergence can also occur (perhaps more commonly!) If an ancestral population is divided into two or more by changes in geography: because natural selection works by chance survivals, it is unlikely that exactly the same variations of the ancestral population will survival in the two or more separated populations.

Over time, if the populations meet again, the accumulation of variations may be significant enough that they are distinct species. II. So, in review: III. Timeline of evolution. Evolution Library. Evolution: Deep Time Timeline. Baba Brinkman’s Rap Guide to Evolution. Science and hip-hop? “Never the twain shall meet,” you may cry, and until recently, I’d have agreed with you on that one, fo’ shizzle. But then I stumbled across a collaboration which challenges that assumption. Baba Brinkman’s Rap Guide to Evolution is interesting, intelligent and funny hip-hop about evolutionary theory. It’s the first peer-reviewed rap, and almost certainly the only hip-hop album that features samples of Richard Dawkins reading from Darwin’s “On the Origin of Species” (other examples in the comments section please). The video below, “Natural Selection”, has its tongue firmly in its cheek, featuring a dance-off between Darwin and some of his best-known opponents, including the perennial favourite, God, and a more modern proponent of creationism, Sarah Palin.

Fellow SciAm blogger Kevin Zelnio wrote about Baba back in November, but this unique rapper warrants a bit more attention – and a few links to his official music videos. Evolution: Isn't Evolution Just a Theory? Evolution: 24 myths and misconceptions - life - 16 April 2008. If you think you understand it, you don't know nearly enough about it It will soon be 200 years since the birth of Charles Darwin and 150 years since the publication of On the Origin of Species, arguably the most important book ever written. In it, Darwin outlined an idea that many still find shocking - that all life on Earth, including human life, evolved through natural selection. Darwin presented compelling evidence for evolution in On the Origin and, since his time, the case has become overwhelming.

Countless fossil discoveries allow us to trace the evolution of today's organisms from earlier forms. And yet despite an ever-growing mountain of evidence, most people around the world are not taught the truth about evolution, if they are taught about it at all. For those who have never had the opportunity to find out about biology or science, claims made by those who believe in supernatural alternatives to evolutionary theory can appear convincing. Shared misconceptions: Promoted Stories. History of evolutionary thought. Evolutionary thought, the conception that species change over time, has roots in antiquity, in the ideas of the ancient Greeks, Romans, and Chinese as well as in medieval Islamic science.

With the beginnings of biological taxonomy in the late 17th century, Western biological thinking was influenced by two opposed ideas. One was essentialism, the belief that every species has essential characteristics that are unalterable, a concept which had developed from medieval Aristotelian metaphysics, and that fit well with natural theology. The other one was the development of the new anti-Aristotelian approach to modern science: as the Enlightenment progressed, evolutionary cosmology and the mechanical philosophy spread from the physical sciences to natural history. Naturalists began to focus on the variability of species; the emergence of paleontology with the concept of extinction further undermined the static view of nature. Antiquity[edit] Greeks[edit] Chinese[edit] Romans[edit]