If we do not act responsibly, we confront the sixth, and perhaps definitive, great extinction of the Earth. Despite the initial resistance to the Darwinian vision, at the beginning of the 20th century the idea of the evolution of life was already accepted by most Christian confessions. However, in the South and Midwest of the US, numerous and very active groups of evangelical Christians have repeatedly tried to prohibit the teaching of evolution in schools or share it in time and scientific recognition with the Biblical account of Genesis.
In recent times, creationists have been renewed and organized through the intelligent design movement, gaining adherents of other confessions.
Fundamentalists give supreme value to a text written more than 2, years ago in a historical and cultural context that has nothing to do with the current one, and that still consider it more credible than the whole body of knowledge, empirical data and theoretical structures that thousands of endowed minds of our species have developed working together for the last years.
The universalization of the practice of science has not translated into the adoption of a common worldview of the Universe and life. The persistence, a century and a half after the Origin of the species, of openly antiscientific beliefs is a great paradox of our time. The attainment of a universal Darwinian-based creed would lead to a higher plane of consciousness of the human species and would undoubtedly be Darwin's greatest legacy.
See the article Darwinism - Creationism written by the author. The morphological, biochemical, and genetic similarities place the human being in the order of primates of the mammalian class. Within primates, they are the chimpanzee, the gorilla and the orangutan, their closest relatives. The sequence comparison data show that there is a similarity of This resemblance is greater than that between the chimpanzee and the gorilla or the gorilla and us, so the chimpanzee and humans share a more recent common ancestor than both with the gorillas.
This closeness, which has been estimated around 6M years, is much greater than what was inferred only with morphological data, and shows the ability of DNA data to reveal kinship relationships. In human evolution there are two major acquisitions, the bipedal gait, and the extraordinary development of the brain. The fossil record shows us that the upright posture preceded brain development and that Africa is the cradle of humanity. Australopithecus , 1.
His cranial capacity was similar to that of the current chimpanzee and gorilla. Homo habilis and Homo erectus are the lines that follow chronologically until the arrival of our species, Homo sapiens , , years ago. Current phylogeny of modern humans and anthropomorphs that integrates molecular and morphological data. In , the genome sequence of mitochondria DNA from the first fossil found in Neanderthal man, an extinct subspecies of the human species, was published.
It was the first time that the molecular sequence of a hominid fossil was obtained. When the sequence was compared with homologous sequences of current human DNA it was inferred that the common ancestor of us and Neanderthal man lived , years ago, from which it was tentatively concluded that the Neanderthal man became extinct without mixing with the current man. The Future of Evolution. With the appearance of the human brain, a singular fact occurs: the emergence of objective consciousness in the biosphere.
We are sparks of consciousness in a Universe that until our irruption was blind and deaf to its becoming. For the first time, and in a recursive sense, the universe thinks of itself when we discover its existence in the same way that we think and discover ourselves with our brain. This constitutes the most transcendental moment of the whole evolution.
The scientific thinking that results from the activity of minds working collaboratively to understand the physical, biological and mental reality of our universe leads us to higher levels of consciousness.
Scientific and cultural evolution is not limited to the laws of natural selection and genetic inheritance. It follows a process of horizontal transmission between individuals of one generation and vertical transmission between generations that is much faster than the typical processes of biological evolution.
We will greatly limit the hazards of mutation, genetic segregation and gamete union. Mutated genes that cause serious diseases to the human species may be replaced by their non-deleterious counterparts. But paradoxically humanity is today facing the challenges of its own evolutionary success.
The explosive growth of its population, with the needs of space and resources that it generates, causes the elimination or reduction to unbearable sizes of the habitats of the species. The current extinction rate is not sustainable. It is possible that the human being can maintain biological diversity in the form of seeds or frozen cells, and even that it can compensate for the loss of species with the creation of new ones through genetic engineering.
But the drastic reduction of natural spaces will inevitably limit diversity. Humankind's great challenges are the control of population growth, the elimination of socio-economic inequalities, the maintenance of sustained and viable development and the conservation of natural habitats and species.
Success in the face of such challenges requires the development of a universal ethical conscience based on respect for the diversity of peoples and cultures of our species. This awareness must extend to encompass the totality of life, the precious set of organic forms that have accompanied us, from the first common ancestor cell, in this fascinating singular and unrepeatable journey that is our biological history.
Humanity will soon be able to replace deleterious mutated genes with their healthy counterparts. Antonio Barbadilla. Nothing makes sense in biology except in the light of evolution Theodosious Dobzhansky.
Darwinian Revolution Although the idea of evolution had precedents, it was not until , with the publication of the work The origin of the species of the British naturalist Charles Darwin, that biological evolution was definitively established as explanation of diversity of life.
Darwin's solution was to propose the mechanism of natural selection Paley's design argument had a great influence on nineteenth-century naturalists, despite the fact that this interventionist vision flagrantly violated the concept of nature that had been established with the development of physics in the sixteenth and seventeenth centuries. Charles Darwin To make his theory of evolution and natural selection intuitive, Darwin had to introduce a new way of understanding variation in nature: Population Thinking.
The Fossil Record The sediments that have accumulated on the earth's crust during its geological history leave an inestimable trace, generally in the form of bones or hard petrified skeletons, of dead organisms in the past: these remains are the fossils.
The Geological Time The geological time has been divided into a series of hierarchical stages, the ages, the periods, and the epochs, which do not follow a linear chronology, but rather chronicle the key moments of the history of life.
Chronology of Seven Stellar Moments of Evolution What does the fossil record teach us about the history of life on Earth? The torch goes from dinosaurs to mammals 65 M Origin of Homo sapiens 0. Evolution has no Definite Direction The history of life is a story of extinction and death Mass Extinctions There are two extinction regimes: normal extinction, which affects species that fail to follow their environment in their daily struggle to adapt, and mass extinction, which are faster and more devastating in its magnitude.
The Fauna of Burguess Shale If we had the opportunity to return to a moment in the past, the period before the Cambrian would undoubtedly be one of the most attractive. Opabinia: a Strange Life from a Remote Past Opabinia was the fossil of Burguess Shale that revealed the box of surprises that there was in this deposit.
The Dinosaurs During the Triassic period, dinosaurs from a line of reptiles emerge and initiate a dynasty over the terrestrial environment that would last M.
Comparative Biology: Homology and Analogy When one observes similarities between species, one can distinguish between two types of similarities, analogy and homology. Homology: all tetrapods have a limb with five fingers, although they have different functions Homology is the Basis of Classification The classification is based on the comparison of the characters of the species, and the homologous characters are the key elements to establish an evolutionary classification.
Vestigial Organs An especially significant case of homology is that of vestigial or residual organs. Molecular biology and homology Molecular biology has provided the most universal evidence of homology. DNA is a helical molecule that has genetic information encoded from four different letters or nucleotides The Tree of Life: Phylogeny If the history of life is change and branching by descent, then its representation would be that of a tree or phylogeny , in which the trunk and internal branches would correspond to the ancestors of the current species and the ends of the outer branches would be the current species.
Let be a given organism and time-step. Then, in the next step the organism is mutated to. The fitness function selects whether the new organism survives or fails:. Chaitin's deep insight into the problem of biological evolution is the choice of the fitness function from AIT. The idea is to see life as evolving software, such that a living organism is tested after a mutation has occurred.
The idea is to use a testing function that is an endless resource. This way, evolution will never be exhausted, will ever go on. In AIT there are several functions with this remarkable property that make them specially well-suited for this task: quantities that are definable but not computable. One example is the Busy Beaver function For the Busy Beaver function there are several variants which are equally good for the purposes of fitness function, that measures the rate of evolution.
To work with it is convenient to specify the maximum size N that the programs operated by U and define the output as the largest integer in binary form that is computed after halting U. Thus, a N -th Busy Beaver function is denoted and defined. This is a well-defined function but it is noncomputable: it grows faster than any computable function for sufficiently large N.
Therefore, cannot be bounded in the form of. This is the property that makes a good candidate for fitness function since it is an endless source of creativity that enable us to test a new organism, a program and see whether it is smarter by checking whether it can name a bigger number.
Thus, we can use 4 with and ask how the total mutation time T N behaves as N grows. Let us mention in passing that naming increasingly bigger numbers requires lots of creativity in the form of new functions and ways to name new numbers bigger and bigger. To define it, it is convenient to introduce the notion of universal probability P U x of a given string :. That this is a well-defined probability distribution is a central result in AIT.
It relies on some technical details: a the programs p are not arbitrary, but self-delimiting; b convergence of the series is guaranteed by the Kraft inequality A self-delimiting program is a program that knows when to stop by itself, without additional stopping symbols.
It is constructed from a set of prefix-free strings of bits: strings that are not prefix of any other string in the set see Methods section III. In AIT, the algorithmic complexity and the universal probability of strings are related by a Shannon type of equation:. It is considered as the halting probability in the theory of TMs.
It measures the probability that a randomly chosen program p will halt when run in a UTM that halts. Thus, it is defined on the set of prefix-free halting programs, not for arbitrary programs. Interestingly enough, Chaitin proved that universal TM exist for self-delimiting programs. It hosts an inexhaustible amount of knowledge and it is thus suited for a fitness function. Like , it is convenient to truncate Chaitin's number up to programs of size N computed in time less than N :.
To complete the construction of the organism from the proto-organism , we need two more ingredients. Altogether, the organism looks like:. According to AIT, a natural move is. Notice that this mutation induces, in turn, a mutation in the organism by the rules specified in its construction above. To this end, the fitness function is introduced as follows:. As Chaitin notices, this implies the use of an oracle 2 , 3 , 4.
Let us denote T N the total mutation time, i. Depending on the strategy followed by Nature, Chaitin considers three scenarios and computes the scaling of T N with N. In this way, one can assess which is the best evolutionary scenario.
The results are the following:. This scenario represents that there is no strategy in Nature and every possible organism is tested regardless which was the previous organism that originated it. Thus, there is no effective application of a fitness function but Nature explores all possible codes available in the phase space. It takes an exponential time to reach a certain organism.
This scenario is the opposite to the previous one. Now, Nature is not dumb but assumed to be intelligent enough so as to know about AIT and this model of evolution. The initial proto-organism is. Thus the mutation time takes of the order of N trials:. A more natural assumption is that Nature choses randomly the mutations among the set of possible mutations.
It is a random walk in the space of mutations. Remarkably enough, the evolution time grows in between quadratic and cubic in N :. Although this is worse than scenario II, it is still a polynomial growth and far from the exponential growth of scenario I. The following definitions are we well-motivated when trying to bring concepts from Quantum Information Theory QIT into Chaitin's classical model.
They can be made even more general as discussed in Sect. Quantum Organism : it is a pure quantum state in a Hilbert space of infinitely countable qubits:. In practice, we shall be dealing with a finite truncation to a number of qubits N denoted as.
The meaning of this choice is motivated by the notion of classical organism as a program for a TM. Now, the quantum version is a pure state that encodes the information of a quantum program. This is meaningful since we have adhered to an abstraction process in which a living organism is divested of everything except its genetic code that is represented by a classical program.
Thus, a quantum organism is not a form of quantum life, but represents quantum effects in the classical code of DNA. Quantum Mutation : it is a quantum algorithm that transforms the original quantum organism into a mutated quantum organism :.
Quantum Fitness : it is a cost function that selects a mutated organism when it is fittest than the original. The traditional characters of Quantum Information 20 , 21 Alice A and Bob B , can be adapted to the quantum evolution scenario: Alice is the organism before the mutation and Bob is the mutated organism.
Then, will success or fail depending on the fitness of the pair A , B. In order to complete the above quantum definitions we need to specify how to choose a triplet in the quantum case. Once this is done, the quantum notions of mutation and fitness function will also follow.
All this can be done by defining a notion of quantum algorithmic complexity. In fact, there are several versions of H q 22 , 23 , 24 , 25 and not all of them are equivalent. We shall choose the definition of Mora and Briegel 25 that is called network complexity H net because of the following properties 25 , 26 , 27 :. H net is a classical algorithmic complexity associated to a quantum state. It describes how many classical bits of information are required to describe a quantum state of N qubits.
Being classical, it will allow us to compare to previous evolution rates on equal footing. H net has the special property that it requires an exponential number of classical bits for the description of generic quantum states. In particular, it detects a sharp difference between multipartite entangled states and separable states.
The network complexity is a description that Alice does of a quantum state she has and she wants to send this information to Bob through a classical channel so that Bob could eventually reproduce that state on his side.
It describes the classical effort Bob would have to do. With the aid of these elements, we can construct a mapping from quantum states in to finite strings , such that. The first equality represents our choice of quantum algorithmic complexity while the second is the definition of network complexity 1. The mapping 19 is constructed from the elements a -c as follows: let us select a universal finite set of gates for example, the one generated by the gates 28 , i.
Then, Alice sets up a quantum circuit of gates called U by concatenating gates from and constructs a state, namely, , from an initialization state. This prepared state can approximate the desired state with precision given by. This is represented by a certain string of bits , where M is the length of the resulting bit-string and is a certain function of the number of qubits N. Then, the mapping 19 is given by.
With this, the network complexity 20 is well-defined. An additional minimization process is assumed in 1 since the circuit U is not unique and it is natural to request to use the minimal circuit that prepares the state with the desired precission. Our choice of quantum algorithmic complexity has very important consequences for studying quantum effects in biological evolution:.
According to this definition of quantum algorithmic complexity in terms of a classical network complexity, we realize that the set of quantum states is mapped onto the set of bit-strings. Thus, while the former is uncountable, the latter is infinitely denumerable. In a traditional quantum information scenario, Bob needs to agree with Alice on which alphabet to use in order to communicate.
In a quantum evolution scenario, there is no need to agree on a common language for the description since there are not two observers, but a single organism that evolves. We shall use the following fundamental results from network complexity and quantum states Furthermore, the network complexity quantifies very differently the complexity of separable and entangled states 25 :.
Separable States :. Maximally Entangled States :. The fact that separable states are less complex than entangled states means that separable states are more likely: If we type a random bit-string at a computer, most likely it will correspond to a separable state. This raises a fundamental question: can we use the higher complexity of entangled states to accelerate the rate of biological evolution? Thus, we shall use the basic results on network complexity H net. However, we can define Omega numbers associated to selected classes of states.
By construction, these sets are discrete since we are using a discrete set of universal quantum gates. Separable number:. To do this sum, we construct all possilble separable states and apply the mapping 19 to perform the sum. As the method is constructive, the separable states are obtained on demand. Entangled maximally number:. The decision problem of whether a given constructed state is maximally entangled is solved by computing its Schmidt measure and testing that it is maximal.
We take this as an operational definition of maximally entangled state in this context. In both sums, the programs p S and p E are assumed to be prefix-free in order to guarantee their convergence. A scientific theory therefore describes a higher level of understanding that ties "facts" together.
A scientific theory stands until proven wrong -- it is never proven correct. The Darwinian theory of evolution has withstood the test of time and thousands of scientific experiments; nothing has disproved it since Darwin first proposed it more than years ago. Indeed, many scientific advances, in a range of scientific disciplines including physics, geology, chemistry, and molecular biology, have supported, refined, and expanded evolutionary theory far beyond anything Darwin could have imagined.
Learn More Evolution Revolution. Just as the tree of life illustrates, all organisms, both living and extinct, are related. Every branch of the tree represents a species, and every fork separating one species from another represents the common ancestor shared by these species.
While the tree's countless forks and far-reaching branches clearly show that relatedness among species varies greatly, it is also easy to see that every pair of species share a common ancestor from some point in evolutionary history. For example, scientists estimate that the common ancestor shared by humans and chimpanzees lived some 5 to 8 million years ago. Humans and bacteria obviously share a much more distant common ancestor, but our relationship to these single-celled organisms is no less real.
Indeed, DNA analyses show that although humans share far more genetic material with our fellow primates than we do with single-celled organisms, we still have more than genes in common with bacteria.
It is important to realize that describing organisms as relatives does not mean that one of those organisms is an ancestor of the other, or, for that matter, that any living species is the ancestor of any other living species. A person may be related to blood relatives, such as cousins, aunts, and uncles, because she shares with them one or more common ancestors, such as a grandparent, or great-grandparent. But those cousins, aunts, and uncles are not her ancestors. In the same way, humans and other living primates are related, but none of these living relatives is a human ancestor.
Learn More All in the Family. Members of one species do not normally interbreed with members of other species in nature. Sea nomad people from Southeast Asia testify to humans' versatility and endurance.
While using a novel, genetically modified ferret to investigate microcephaly, researchers stumble across clues as to the evolution of our large brains.
Although the evolution of facial characteristics is a complex subject, new research offers a climate-based explanation of the variation in nose width.
Are humans still evolving? Natural selection requires variation. The milk revolution. The Framingham Heart Study. Why are the Dutch so tall? Share on Pinterest Why are men from the Netherlands so tall? Public Health. Exposure to air pollutants may amplify risk for depression in healthy individuals. Costs associated with obesity may account for 3. Related Coverage. Schizophrenia: A byproduct of the brain's complex evolution?
Have some humans evolved into real-life merfolk?
0コメント