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shocking announcement for Thursday: extraterrestrial life?

quote the following story:

What hateful ads are ads! When are things which we intuit to be bombastic, of course. In that position we left NASA to announce that on Thursday announced "a discovery astrobiology that will impact the search for evidence of extraterrestrial life. " It does not say anything specific, but also says a lot.
never hurts to mention that astrobiology is the science that studies the origin, presence and influence of life in the universe, through astrophysics, biology and geology. Then, in the words of the call for the Space Agency to his press conference, one can not help wondering if they discovered any life on another planet.
addition, if a breakdown of the panel of experts will be present at the announcement, one can sense something else: It consists of a geobiologist who wrote about life on Mars an oceanographer who did the same with photosynthesis using arsenic, a biologist who studies the program's largest moon of Saturn ... If one goes along parts it gets quite interesting.
Anyway, I think so will be important and not the typical Apple Voladero lights. Although we could also get a bit more suspicious and believe that the U.S. would give the world a little pill to make people forget the scandal uncovered by Wikileaks few days ago ...
cachudos Were they? What do you think will tell us the day after NASA?

Link: NASA astrobiology sets news conference on Discovery (NASA via Slashgear)

Source: SlashGear (http://www.fayerwayer.com/2010/11/nasa-anuncia-que-anunciara-un-impactante-anuncio-el-jueves-% C2% BFvida-alien /) Let's see what happens

with this, we introduce the following tests on the possibility of extraterrestrial life, as it might evolve, if it could be based on other chemicals other than carbon, etc. Stay tuned!.

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"" Unit Type "or" conditions "?

In this essay we introduce an interesting debate that arose in the nineteenth century, with the participation of outstanding biologists. This debate started by the observation of the very specific present in the animal kingdom, some looked at the feet of many animals, the wings of many birds, each bone, each structure and hence there were two explanations for their origin:

• Existence Conditions: This position, defended mainly by Georges Cuvier, a great paleontologist but also a staunch creationist (position which holds that species have been independently created and not evolved from a common ancestor), said that different species have been created for various "conditions", that is why the wing of a penguin is used mostly for swimming, the wing of a hawk used to efficient flight, the leg of a horse used to run long distances, etc. In short, Cuvier was based mostly on differences structures between animals with a teleological view (based on function).
• Unit Type: This position was defended mainly by Étienne Geoffroy, which was supported by many evolutionists of the time (including Charles Darwin). They focused more on the similarities than differences. They noted, for example, that all vertebrate forelimbs have the same bone structure as follows:

A typical forelimb with estilópodo, and self-power zeugópodo

They observed that on this basis are built all the wings, legs and arms available as follows:

therefore concluded that there were no real conditions of existence, what existed was a "Unit Type", a common pattern which is built on different varieties depending on the ecological context of the animal. In addition, these varieties can be explained by natural selection, without having to resort to a supernatural agent to generate them.
Over time, the position lost Cuvier credibility and position and Darwin Geoffroy been gaining more weight, and that what they observed, after all, was how evolution generates specificity using always the same elements (which, as we have seen, occurs at the molecular level).

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If evolution is a fact, where are the intermediate fossils?

This is something that people often ask, the question assuming that there are no intermediate fossils. The truth is that it is not easy for an animal of the past fossilize, as they require special conditions, as well as some parts of this that can mineralize "forever", as the bones. Therefore, finding fossils of invertebrates is virtually impossible (unless they have shells or the like). However, paleontology has taught us that there are indeed fossils that allow us to observe the transition from one species into another, sometimes very clear, as in the case of whales. Let the great biologist Richard Dawkins explain us this:



Another fossil that allowed us to understand the transition between fish and tetrapods (four-legged land animals) was Tiktaalik roseae, a fish of the Devonian, dating back some 375 million years, which is described by the following Wikipedia way:
"Tiktaalik was primarily the characteristics of a fish, but with the tips forming skeletal structures similar to an arm, similar to those of crocodiles, including shoulder, elbow and wrist. He had the sharp teeth of a predator, and his neck was move independently of his body, it is not possible in other fish. The animal also had a flat skull and the crocodile; eyes on top of the head, suggesting that spend much time looking up, neck and ribs like those of tetrapods, which will serve to support the body and help you breathe through the lungs, a long snout able to hunt dams on earth, and one gill opening, in more advanced animals would become heard. Its discoverers felt that, in all likelihood, Tiktaalik flexed its proto-limbs in the main river bed and could have pushed himself to the shore for brief periods. These specimens reached a size of 1.2 to 2.75 meters. "
If you do not imagine it, Tiktaalik had the following appearance:

In this diagram we can understand how did the transition from water to land:

Such examples are many more. Paleontology offers a grain of sand in favor of the theory of evolution, slowly but surely, and probably even many spectacular fossils waiting to be discovered.

Sources on Tiktaalik:

• http://es.wikipedia.org/wiki/Tiktaalik
• http://www-news.uchicago.edu/releases/06/060405.tiktaalik.shtml

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Pax-6 and the appearance of the eyes

As we all know, the eyes are organs that allow us to detect light, which is absolutely essential for many organisms. However, in biology classes as we just explained how the human eye (assuming no others). The reality is that there are many different solutions to see (and if not expected, the human eye is not the best). Here are some types of eyes distributed in nature:

With so many eyes, some on camera and other compounds (such as fly's eyes), one might think that must have appeared so completely independent and that the genes' builders eyes "of a fly short of a mouse or an octopus. However, this is not true. Quite the contrary, there is a master builder of an eye, called Pax-6, a highly conserved homeotic gene (more We'll talk about homeotic genes).

Such is the level of conservation of this gene, if one takes a Pax-6 in a mouse or a squid and run it in a fruit fly (Drosophila melanogaster ) that can not use its own gene, are generated fly's eyes! (Go back and read this again to size it!). Also, if one expresses this gene ectopically in the legs of a fly eye on its legs generate . The same goes for a frog, we ectopically generated lenses. This is because Pax-6, as several other genes are master keys, ie the first switch is switched on it says "build an eye here." Thus, under his command are all eye specific genes of each species. It must be said that this gene is present with great conservation in mammals, amphibians, amphioxus (a cousin of vertebrates), sea urchins, squid, worms, etc.
What explains this? Drawing on the theory of evolution is very simple to explain and predict: The common descent. A very distant common ancestor this gene had worked so well that simply was distributed around as that the species diverged from each other. But what is known ancestor was? The answer is yes, is the ancestor Urbilateria, an animal that gave rise to two major groups, the protostomes (worms, mollusks and spiders, among others) and deuterostomes (sea urchins, starfish, vertebrates and of course us)

Urbilateria The ancestor is in the second paragraph of this phylogenetic tree marking

This not only happens with the eyes, about many structures that at first glance look totally different, but that when we reduce it to genes, we began to speak a common language. That language is the evolution.

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Ernst Haeckel and the "Stage phylotypes"

As promised and after a long absence (I was at a conference of Developmental Biology in Santa Cruz, Chile), today talk of Ernst Haeckel, a German biologist who made a remarkable observation. He observed that no matter what kind you are, the early embryos are all more or less the same! I leave a drawing by the famous, try not to read the names below and see the first row of embryos, guess which species corresponds to each, if you go down each column represents time in development:

The answer is as follows, from left to right: Fish, salamanders, turtles, chicken, pork, veal, rabbit and of course, a human being (again we realize that we are not as exclusive.) This is what Haeckel postulated as the "recapitulation theory" claiming that "ontogeny recapitulates phylogeny," but what does that mean?, We must define the terms:

• Ontogeny: This is the development of an organism , since it is an egg until it becomes an adult, is the definition of "philosophical" in the subject matter of developmental biology
Phylogeny
• This is a more familiar term that describes the evolutionary relationships between species in this planet.

So what Haeckel wanted to say very elegant, is that the development of an organism may be a reflection of their evolutionary history in a more or less linear (that is currently not accepted in their literal form, not is that the development go through fish, reptiles, mammals, etc ...). Therefore, the more closely related are two species, but its development is similar. On the other hand, the early stages of development of animals of a given group are all basically the same due to the phenomenon of common descent. That is why if one observed in early embryos of vertebrates formalin bottles are not labeled, believe me it will cost a world guess what the human and what is the rabbit or dog.
is this stage of development where all the animals of an edge we are equal, which was called "Stage phylotypes. Recall that we belong to the edge of the chordates, so when we are embryos, we have nothing to envy to the whales, dogs, tigers and turtles.

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How does developmental biology to genetics and evolution?

We first define each concept, then we will try to understand how they hold hands:

• Developmental Biology: This branch of biology, formerly known as the "Embryology" looks like an egg grows into a chicken, or as an acorn grows into an oak. A remarkable fact about this is that these complex processes are orchestrated by the genes!.
• Genetics: This branch is responsible for understanding the biological heritage. The good news is that since Mendel, progress has been made, to the point of being able to understand how genes act at the molecular level.
• Evolution: As we have seen, evolutionary biology is responsible for understanding the relationships between different animals on the planet, common descent and changes experienced by living beings in time.

Now, the union of these 3 concepts is quite apparent, if the development is genetically regulated and if the animals are descended from a common ancestor means that we share many genes in common, so we share common development patterns!. From another point of view, we have an approach to the evolution of animals by observing their development, which many biologists like Ernst Haeckel, as noted and which speak in the next trial.
For now, let's stay with the image of genes that occupy the animals to become what we are all more or less the same, there is a great conservation due to evolution, something that is very simple graphics and clear in the following video:

What are these genes, how the mechanisms of development work? What is the origin of all this?. These and other questions will be addressed during this entire blog. Welcome to a new paradigm of biology, the "Evo-Devo (Evolutionary Developmental Biology), a new way of understanding evolution.

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samurai crabs and artificial selection

I take the liberty of quoting some of pages from the great book "Cosmos" (1980) by Carl Sagan (pages 24, 25 and 26 of the Castilian edition of Metro in 1997, copied from http://www.bauleros. org / elcangrejoheikecarlsagan.html) no one could describe it better than the great popularizer of science:

"Let me tell you a story about a little phrase in the music of life on Earth. In 1185 the emperor of Japan was a boy aged seven called Antoku. was the nominal head of a samurai clan called Heike, who were engaged in a long and bloody war with another samurai clan, the Genji. Each clan claimed to possess superior ancestral rights to the throne. The decisive naval encounter with Emperor on board, occurred in Danno-ura in the Inland Sea of \u200b\u200bJapan on April 24, 1185. The Heike were outnumbered and tactics. Many were killed by the enemy. Survivors were launched in large numbers to the sea and drowned. The Lady Nii, grandmother of the emperor, decided that neither she nor Antoku had to fall into enemy hands. The Story of the Heike account of what happened next:

The emperor had met him seven years old but looked much older. It was so beautiful it seemed to cast a bright glow and long black hair hung loose down her back. With a look of surprise and anxiety in his face he asked the Lady Nii:

- Where will you take?

She looked at the young ruler as the tears rolled down her cheeks y. .. comforted him, tying his long hair in his dove-colored dress. Blinded by sovereign child tears gathered his beautiful hands. First got to say goodbye to the East side of the god of Ise and then face west to repeat the Nembutsu [a prayer to the Amida Buddha]. The Lady Nii took him tightly in his arms and as he said "in the deep ocean is our capitol," he finally sank beneath the waves. Heike
entire fleet was destroyed. Only forty-three women survived. These ladies of honor of the imperial court were forced to sell flowers and other favors to the fishermen near the scene of the battle. The Heike disappeared almost completely from history. But a group formed by the old mob of bridesmaids and their offspring among fishermen founded a festival to commemorate the battle. To this day is celebrated on 24 April each year.
Fishermen Heike descendants of hemp wear black headdress and march to the Akama shrine which contains the mausoleum of Emperor drowned. They attend a representation of events following the battle of Danno-ura. For centuries, people imagined he could distinguish ghostly samurai armies vainly striving to shorten the sea to wash the blood and remove his humiliation.
The fishermen say the Heike samurai wander still funds the Inland Sea, in the form of crabs. Can be found in this sea crabs Weird signs on their backs, and identifications that forms a striking resemblance to the face of a samurai. When fishing a crab of these is not eaten but is returned to the sea to commemorate the sad events of Danno-ura.
This process raises a lovely problem. How is that a warrior's face is engraved on the shell of a crab? The answer seems to be that it was men who made the face. The shadows in the shells of crabs are inherited. But among crabs, as among individuals, there are many different hereditary lines. Suppose that among the distant ancestors of this crab emerged one with a form that appears, even slightly, to a face human. Even before the battle of Danno-ura fishermen may have felt qualms about eating a crab as well. To return to the sea set in motion an evolutionary process: If you're a crab and your carapace is ordinary, men will eat you. You will leave few offspring lineage. If your shell is a bit like a face, I throw them back into the sea. You can leave more offspring. The crabs were of considerable value invested in the forms recorded in their shells. As the generations passed, both crabs and fishermen, the crabs whose shapes were more like a samurai face survived perfectly, until finally it got not only a human face not just a Japanese face, but the face of a fierce and angry samurai. All this has nothing to do with what the crabs want. Selection is imposed from the outside. The more one looks like a samurai better your chances of survival. At the end you get an abundance of crabs samurai.

A crab Heike the Inland Sea of \u200b\u200bJapan.

This process is called artificial selection. In the case of the Heike crab, made it more or less conscious fishermen, and of course without the crabs were meant seriously. But men have deliberately chosen over thousands of years, plants and animals that have to live and who deserve to die. From our childhood we are around animals, fruits, vegetables, trees and family, cultivated and domesticated. Where from? Did they live freely before the wild and then induced them to follow a less harsh way of life in the field? No, the reality is very different. Most of them we did. "