Stories tagged Heredity
Coelacanth: model in the SMM paleo lab. Photo by Mark Ryan.Courtesy Fancy Horse (underwater background)The genome of the coelacanth, the world's best known living fossil, has been sequenced by an international team of researchers and is revealing something scientists already suspected: that the primitive-looking fish has evolved more slowly than most other organisms. The coelacanth is related to the lungfish and several extinct Devonian fish species that are considered precursors to land dwelling tetrapods. Kerstin Lindblad-Toh is senior author of the study which appeared recently in the science journal Nature.
"We often talk about how species have changed over time, but there are still a few places on Earth where organisms don't have to change, and this is one of them," Lindblad-Toh said. "Coelacanths are likely very specialized to such a specific, non-changing, extreme environment -- it is ideally suited to the deep sea just the way it is."
Lindblad-Toh is scientific director of the Broad Institute's vertebrate genome biology group in Cambridge, Massachusetts, which did the genome research. The institute is linked to both MIT and Harvard.
The genetic map, which involved sequencing some 3 billion letters of DNA, also showed (via RNA content) that tetrapods - four-legged land dwelling animals - though related to both coelacanths and lungfish, are more closely related to lungfish and followed that line rather than that of the coelacanth. We humans also branched off that same line. The genome of a lungfish is composed of over 100 billion DNA letters, making it a much more difficult task to sequence, so for the time being, the coelacanth's DNA makes for a reasonable alternative for study.
"This is just the beginning of many analyses on what the coelacanth can teach us about the emergence of land vertebrates, including humans, and, combined with modern empirical approaches, can lend insights into the mechanisms that have contributed to major evolutionary innovations," said professor Chris Amemiya at the University of Washington, and the paper's co-author.
Fossil coelacanth: not much has changed in 350 million years.Courtesy photo by Haplochromis via Wikipedia Creative CommonsWhen Louis Agassiz named the first fossil coelacanth back in 1836, the Swiss paleontologist probably never imagined that a nearly identical descendent of the primitively constructed Devonian-aged fish would one day be found still inhabiting the world's oceans. The coelacanth was thought to have gone extinct along with the non-avian dinosaurs at the end of the Cretaceous period. None have been found in the fossil record after that time, but two extant species are known today. The first specimen Latimeria chalumnae was netted off the coast of South Africa in 1938, near the Chalumnae river and retrieved by East London Museum curator Marjorie Courtenay-Latimer who discovered what she called "the most beautiful fish I'd ever seen" in the catch of local fisherman, Henrik Goosen. Since then several more coelacanths have been caught, including the Indonesian species, Latimeria menadoensis, from the Indian Ocean.
The remarkable prehistoric throw-back, sometimes referred to as "old four legs" because of its leg-like fins, hasn't changed much in its 350 million year history. A member of the clade of lobe-finned fishes called Sarcopterygii, coelacanths retain primitive characteristics such a notochord, a hollow fluid-filled tube made of cartilage that underlies the spine over the length of its body. In all other vertebrates, the notochord is an anatomical structure that appears briefly only during the embryonic stage but not in adults. Not so with the coelacanth. It also possesses, primitive shark-like intestines, a linear heart, and tightly-woven armor-like scales (known as cosmoid) that are only found on extinct species of fish. The coelacanth's brain case contains only 1.5 percent gray matter - the other 98.5 percent of space is filled with fat. The other end of the coelacanth body begins to taper before expanding into a strange, three-lobed tail. Its most notable features are its lobed pectoral and pelvic fins that are structured with bones that look like toes, and move in an alternating tetrapod manner. An electroreceptive rostal organ located in its snout is used to detect prey, and the coelacanth is the only living animal that can unhinge a section of the its cranium to increase the gape of its mouth, enabling it to consume larger prey.
The blue or brown, white-speckled coelacanths prefer deep-water environments, and can reach six and a half feet in length and weigh upwards to 175 pounds. For some reason no living coelacanth has managed to survive more than a single day in captivity. With a dwindling population estimated at only 500-1000 individuals, the coelacanth was declared an endangered species in 1989.
SOURCE and LINKS
Broad Institute news
Coelacanth info at dinofish.com
More coelacanth info
NatGeo article
Take Nova's Coelacanth Quiz
Tags : ![Home at last: Our late cat, Ernesto "El Gato Gordo" Hemingway, seen recuperating after somehow managing to find his way back home from across the street in 1997.](/sites/default/files/images/ernie_chair011.jpg "Home at last: Our late cat, Ernesto "El Gato Gordo" Hemingway, seen recuperating after somehow managing to find his way back home from across the street in 1997.")
Home at last: Our late cat, Ernesto "El Gato Gordo" Hemingway, seen recuperating after somehow managing to find his way back home from across the street in 1997.Courtesy Mark RyanA cat in Florida got loose on one side of the state and managed to find its way back home to the other side, baffling both the delighted owners and scientists. Holly, the directionally-savvy 4-year-old tortoiseshell cat traveled from Daytona Beach to within a mile of her owners’ home in West Palm Beach. It took her about 50 days to traverse the 200 mile distance. When found, the poor kitty was weak and emaciated, had a croaky meow, and displayed signs of hoofing it over long distances.
“Her pads on her feet were bleeding,” said Bonnie Richter, who along with her husband, Jacob, are the happy owners (read: service staff) of the migratory feline. “Her claws are worn weird. The front ones are really sharp, the back ones worn down to nothing.
Skeptics might conjecture that the found cat is merely a stray that just looks like the long-lost Holly, and that the distraught owners only think it’s their cat because they miss her so and want to believe it’s her. Well, they couldn’t be more wrong. The scruffy cat in question had an implanted microchip that proves it is indeed Holly.
The Richters’ tale is but one of many incredible stories about lost or separated pets finding their way back home across vast distances. And surprisingly, science doesn’t seem to have any answers as how the animals do it.
“I really believe these stories, but they’re just hard to explain,” said Marc Bekoff, a behavioral ecologist at the University of Colorado. “Maybe being street-smart, maybe reading animal cues, maybe being able to read cars, maybe being a good hunter. I have no data for this.”
SOURCE
New York Times story
Vision evolution: The compound eye of a 390 million-year-old trilobite, Phacops rana milleri.Courtesy Striving to a goalSomewhere, deep in the recesses of animal evolution, a mass of molecules known as opsin mutated from a run-of-the-mill protein into a detector protein with great vision. Not vision in the figurative way, but vision in the literal way. Opsin is the protein in the photopigments of your eye that interacts with light, and allows you to see all the wonderful things visible in the universe. If you’re reading this post, you have the opsins in your eyes to thank.
Here’s how it works. When a particle or wave of light (a photon) enters your eye, the light sensitive opsin traps it using a small chromophore molecule in it architecture called retinal. Normally, retinal’s tail is all twisted and bent, tensed up, and waiting for something to happen. That’s just the way retinal is when it’s chilling out. But when a photon hits it, the light particle interrupts retinal’s naptime, and the molecule reacts by straightening out its tail. The tail’s movement starts a chain reaction of sorts activating the opsin, which in turn, activates a nearby nerve that shoots out a signal that your brain perceives as light.
Three types of opsin can exist in the eye: R-opsins (rhabdomeric), C-opsins (ciliary, and Go/RGR-opsins (Go-coupled/retinal G protein-coupled receptor). The R and C opsins, depending what type of animal you are (e.g. vertebrate or jellyfish), are used for detecting light. Go/RGR-opsins don’t detect light but are used instead to help regenerate retinal cells and regulate an animal’s inner clock or biological rhythms. Scientists have known about opsins since the 19th century, but haven’t known much on how they evolved, or how they became designated light detectors.
In a recent study published in the journal PNAS, Roberto Feuda of the Department of Biology, National University of Ireland Maynooth, and colleagues reported on their detailed examination of the genetic trail of opsins in all kinds of animal life, from sponges and jellyfish to reptiles, birds and mammals. And while their results warrant further study, they did add new knowledge to our understanding how the eye evolved.
The study negated a long-held idea among scientists that only certain light-designated opsins were present in certain animal types. Generally, C-opsins were thought to be present only in vertebrates, and R-opsins only in invertebrates. But the study showed otherwise. It postulated that all three forms of opsins probably existed in the earliest common ancestor right from the beginning. Later, somewhere along their respective evolutionary lines each group designated the C or R opsins for light detection. The leftover opsins (whether C or R) were used for other non-visual purposes such as setting biological rhythms.
It also pushed the origins of light-sensitive organs back a couple hundred million years from about half a billion years ago to three-quarters of a billion years ago, a time not long after sponges had diverged from other animals and before they split into Bilateria and Cnidaria. Within that evolutionary timeline opsins were found in the gene sequence of the tiny and transparent shape-shifting microorganisms called placozoa. However, because the genome lacks a critical retinal-binding amino acid - lysine 296– it’s unlikely these opsins were able to detect light. (It should be noted that placozoan phylogeny is still under debate). But somewhere along the evolutionary line, these non-visual opsins mutated into a light sensing protein. After just two more gene duplications the three opsins, R, C, and Go/RGR we find in our eye’s photopigments today, were already present in the genome.
Why or when opsins developed into part of the eye’s photopigment is anyone’s guess. This research doesn’t solve all the mysteries surrounding them, particularly their non-visual functions but it does fill in some of the gaps in our understanding of key components of vision evolution.
SOURCES
The Conversation article
Scientific American article
Intro to phyologeny
Evolution timeline from 1882: This caricature of Darwin's theory appeared in the 1882 Punch Almanac. The recent evolution timeline created by Kyrk and Sezen is a bit of an improvement.Courtesy Public domain via Wikipedia This cool evolution timeline is really fascinating and fun to mess around with. I'm guessing Charles Darwin would agree it's a vast improvement over the one that appeared in Punch Almanac in1882 when he was still alive (see image at right). This new one was created by John Kyrk, a biology-trained artist in San Francisco in collaboration with Dr. Uzay Sezen, a plant biologist from the University of Georgia. The timeline is available in several languages and would be very useful in a classroom setting when studying evolution and paleontology.
The site is interactive and follows the evolution of our universe from the Big Bang to the present. You start it by clicking and sliding the red pyramid on the right. As you scroll across the timeline, various events in the history of the Universe, Solar System and ultimately, the Earth show up on the screen. All along, links also appear that either explain concepts or show examples of them. In the upper left hand corner is a menu linking you to several corollary Flash animations by Kyrk explaining cell biology and how RNA, DNA, cells, water, and other basic elements of life (including viruses) operate. Kyrk thinks animated illustrations are very useful in teaching and remembering ideas and concepts.
All the phases of Earth’s formation and development are covered in the evolution timeline, including the Late Heavy Bombardment, Snowball Earth, Cambrian Explosion, stromatolites, photosynthesis and iron formation. Once life begins to rise up, your computer screen will run amok with Earth’s diverse species populations from the one-celled animals, trilobites and fish to amphibians, reptiles, dinosaurs and mammals – the whole shooting match. All the major extinction events are shown, too.
The site also contains a link to this YouTube video version of someone else working the timeline so you can just sit back and watch how it happens, But I recommend working the interactive page yourself. A lot more happens and is available than the video allows you to see. Note that you’ll need Flash for it to run on your computer.
I wonder how Darwin would have reacted if he were able to see his theory illustrated in this way?
SOURCES
Evolution Timeline
R/V Hespérides, docked at Aloha Tower in Honolulu, Hawai`iCourtesy C-MOREHow would you like to be aboard a ship, circumnavigating the globe, collecting samples from the world’s ocean?
That’s exactly what Spanish oceanographers are doing on their Malaspina Expedition aboard the Research Vessel, R/V Hespérides. Scientists and crew left southern Spain in December, reached New Zealand in mid-April, and recently arrived in Hawai`i. The expedition's primary goals are to:
- build upon the historic 1789-1794 Malaspina expedition to promote interest in marine sciences among the Spanish public, particularly the nation’s youth
- collect oceanographic and atmospheric data -- chemical, physical and biological – that will help evaluate the impact of global change
- explore the variety of marine life, including microbes, especially those living in the deep sea
CTD: As this oceanographic instrument is lowered over the side of a ship, each gray Niskin “bottle” can be electronically triggered to collect a seawater sample from a different ocean depth.Courtesy C-MOREIn connection with the latter two goals, the Malaspina scientists met with their colleagues at the Center for Microbial Oceanography: Research and Education (C-MORE). The two groups of scientists are working together. "We can exchange data on the local effects, what's happening around the Hawaiian Islands, and they can tell us what's happening in the middle of the Pacific," said Dr. Dave Karl, University of Hawai`i oceanography professor and Director of C-MORE.
The Malaspina-C-MORE partnership is the kind of cooperation that can help solve environmental problems which stretch beyond an individual nation’s borders. The R/V Hespérides has now left Honolulu on its way to Panama and Colombia. From there, the scientists expect to complete their ocean sampling through the Atlantic Ocean and return to Spain by July. Buen viaje!
Archaeopteryx: Thermopolis specimen.Courtesy Mark RyanThis year marks the 150th anniversary of the announced discovery of the first fossils of Archaeopteryx, a remarkable chimera of both bird and reptile traits. The first evidence identified was a single feather discovered at a limestone quarry in Solnhofen, Germany. This was in 1860. The German paleontologist Hermann von Meyer described the fossil in 1861, naming it Archaeopteryx lithographica. That same year, the first skeletal remains came to light, and although headless, the London specimen, as it became known, showed clearly both avian and reptilian characteristics.
The unique and iconic fossil appeared just two years after publication of Charles Darwin’s On the Origin of Species and helped bolster the naturalist’s theory of evolution through natural selection because its appeared to be a transitional fossil between reptile (dinosaur) and bird. Could Darwin have asked for any better evidence?
Since then nine other specimens have been found, including the Berlin specimen around 1877, which is considered one of most complete. For many years some Archaeopteryx specimens languished in collection drawers because they had been initially misidentified as another creature entirely. In 1970, Yale paleontologist John Ostrom was investigating a so-called pteradactyl fossil at a museum in the Netherlands, when he realized it had been misidentified and was actually an Archaeopteryx. The fossil had been found at Solhofen in 1855, five years prior to the feather! The museum curator was so shaken by Ostrom’s announcement, he clumsily wrapped the specimen in a paper bag and presented it to Ostrom so he could take it back to Yale for further study. Ostrom, by the way, re-ignited the “birds are dinosaurs” debate in the 1960s after his discovery of Deinonychus and his comparison of its structural features with those of birds.
The Thermopolis specimen, the latest Archaeopteryx fossil, became known around 2005 and was donated anonymously to the Wyoming Dinosaur Center in Thermopolis, Wyoming. I happened to visit the museum in June of 2007 during the first week the fossil went on public display, and was able to see the spectacular specimen firsthand. The small fossil (about 1.5 feet square) was displayed behind a small, glass opening in the wall. There was no crowd to speak of so I was able to take in and photograph the fossil for a long stretch of time by myself. Looking at it, your eye is immediately drawn to the distinct feather impressions evident on both its wings and tail. The head, arms, and legs are spread out across the slab, and even though it died 150 million years ago, it looks as flat and fresh as road kill on a modern highway.
About the size of a large crow, Archaeopteryx was an odd amalgam of both bird and reptile. It had slightly asymmetrical flight feathers, wings, and a furcula (wishbone) - all traits found in birds. But its pelvis, skull and sharp teeth were reptilian (although some skull features are bird-like), and it ha a long tail like a reptile. Its bones weren’t hollow, like the bones of modern birds are, nor is its sternum (breastbone) very pronounced; it’s flatter and without a large keel where, in birds, muscles flight are attached. And it also possesses gastralia (“belly ribs”), a feature found in reptiles and dinosaurs. The inner toe (the hallux) in the Thermopolis specimen doesn’t appear to be reversed so it couldn't grasp or perch and was probably more earth-bound than arboreal. Interestingly, its second toe was extensible – meaning it could be pulled back and elevated for tearing into flesh, just like the middle toes of such dinosaurs as Troodon and Velociraptor. Truth be told, if its feathers hadn’t been preserved, Archaeopteryx would have been classified a carnivorous bipedal dinosaur. In fact, one of the existing Archaeopteryx fossil was first identified as a Compsognathus until preparation revealed its feathers.
Solnhofen and much of Europe in the Late Jurassic: A cluster of islands off the coast of the North American continent.Courtesy Ron Blakey, NAU GeologySo what kind of environment did Archaeopteryx live in, and why are its fossils so well preserved? Well, during the Late Jurassic, southern Germany and much of the rest of Europe were pretty much a group of large islands poking out of the Tethys Sea off the coast of North America. What is today the Solnhofen quarry was then part of an island lagoon protected by a barrier reef. Geological evidence in the strata suggests the lagoon dried up several times followed by periods of re-flooding with seawater. Mixed into a brackish soup of coral debris and mud, and in a warm climate conducive to rapid evaporation, the lagoon’s bottom water levels became anoxic, that is depleted of oxygen. Low oxygen meant less bacterial activity and subsequently slow decomposition of any organism that happened to die or get swept into the stagnant lagoon. Burial in the carbonate muck was swift, leaving fresh carcasses no time to be pulled apart by currents or scavengers.
Solnhofen limestone has been used for centuries as a building stone. Because the rock’s matrix is so fine and splits so evenly (sediment deposition likely occurred in very calm waters), the material was later quarried to produce stones for lithography, a printing technique first developed in 1796, and the source of Archaeoperyx’s species designation. Many early scientific illustrations, including some of the first images ofArchaeopteryx were preserved as lithographs created using Solnhofen limestone.
Archaeopteryx commorative coin: Germany will issue the 10 Euro coin in the summer of 2011Courtesy Federal Republic of GermanySolnhofen’s fossil record shows that the lagoon’s biological population was diverse. Fish, turtles, lizards and insects, crocodiles, crustaceans, ammonites, squid and starfish, mollusks, pterosaurs, and even the soft remains of jellyfish are preserved in the fine-grained limestone. But the premiere creature is of course the Archaeopteryx, which remains the earliest bird (or most bird-like dinosaur, if you will) known to date. As research on existing specimens continues and new fossils appear it's exciting to imagine what advances will take place in the dinosaur-bird connection debate. Whatever happens, Archaeopteryx lithographica will remain one of the most significant and iconic fossils ever discovered. It's no wonder that later this year on August 11th, the Federal Republic of Germany will issue a 10 Euro silver coin to commemorate the 150th anniversary of the discovery of its most famous fossil.
SOURCES and LINKS
Witmer Lab Archaeopteryx blog
UCMP Archaeopteryx page
Solnhofen limestone of the Jurassic
Oh! The humanity!!: Thanks to evolution, being human has its quirks.Courtesy DjenanWhat is it with goosebumps? Why do the little hairs on our skin stand up when we're frightened or cold? What's the point? How come many of us suffer from backaches? They aren't really conducive to productivity, so why have do we have them. What about hiccups? Are they really necessary? I know they can draw attention to ourselves, but do they really help us attract mates or find food? And speaking of food, why do we insist on stuffing ourselves with more and more of it even after we're obviously full and headed toward obesity? Do these quirks in the human organism serve any purpose whatsoever? The answer is: not really; they serve no purpose at all - at least not now. But somewhere way back in our distant past they did. So if they’re useless now, why do we still have them? Well, you can thank evolution for that. Some evolved characteristics - regardless if they serve a purpose anymore - are just passed on down the genetic line. Evolution doesn't really care, it just keeps on keepin’ on. So if want to know where these and other ancient (and now useless) traits originated, check out the Smithsonian.com's The Top Ten Daily Consequences of Having Evolved. It makes you wonder: how will we humans evolve in the future, and what present day traits passed on to our descendants will they'll find useless and annoying? Let us know if you have any ideas.
An Atlantic salmon: slightly GMOed (by me).Courtesy Hans-Petter FjeldBuckle up, Buzzketeers, because school is in session.
Did I just mix metaphors? No! You wear seatbelts in my school, because they help prevent you from exploding.
But you will probably explode anyway, because you are going to get taught. By JGordon. About the future.
Here’s your background reading: a GMO is a genetically modified organism—a living thing whose genetic material has been altered through genetic engineering. Humans have been genetically modifying plants and animals for thousands of years (by selectively breeding them for desired characteristics), but it’s only been in the last few decades that we’ve gotten really fancy and fast about it.
While in the past, or what I like to call “the boring old days,” it took generations to breed crops that produced high yields, grew faster, or needed less water, we can now do that sort of thing in an afternoon. (Well, not really an afternoon, but these aren’t the boring old days, so we should feel free to use hyperbolic language.) We can insert genes from one plant into another, bestowing resistance to pests or poisons, or increasing the nutrition of a food crop.
Pretty cool, right? Maybe. GMOs tend to make people uncomfortable. Emotionally. They get freaked out at the thought of eating something that they imagine was created like the Teenage Mutant Ninja Turtles. Most people prefer to eat stuff that was created the old fashion way: through SEX.
Once they’re in your tummy, GMOs are probably pretty much the same as any other food, really. However, there may be other reasons to approach them cautiously. Most organisms make a place for themselves in their environment, and their environment makes a place around them, and things tend to work pretty well together. But GMOs are brand new organisms, and it can be very difficult to tell how they’ll fit into the rest of the natural world. Will they out-compete “natural” organisms, and cause them to go extinct? Will they interbreed with them, and introduce new weaknesses to previously strong species? The repercussions of such events could be… well, very bad.
On the other hand, GMOs could provide food—better, more nutritious, easier to grow food—for people and places that really need it. And with global population expected to increase by a few billion people before it stabilizes, we’re going to need a lot of food.
Just like everything else, this stuff is complicated. Really complicated. But the issue isn’t waiting for us to get comfortable with it before it pushes ahead. Hence, our main event: GMO salmon.
You might not have devoted much mental space as of yet to mutant ninja salmon, but you will. See, transgenic salmon (i.e., salmon with genes from other animals) may be the first GMO animal on your dinner plate. Or whatever plate you use for whenever you eat salmon. If you even use a plate, you animal.
What’s the point of the GMO salmon? In the right conditions, they grow much faster than their normal counterparts, and they require about 10% less food to reach the same weight as normal salmon. The company responsible for them, AquaBounty, has been working on the project for more than 20 years. Inserted into a commonly farmed species, the Atlantic salmon, the final, successful combination of genes comes from Chinook salmon (a closely related, but much larger species) and the ocean pout (a slightly eel-like fish that can tolerate very cold water). While Atlantic salmon typically only grow during the summer, the new variation produces growth hormones year round, so they can grow to marketable size in about 60% of the time it would normally take, assuming they’re kept in water that’s at the right temperature, and given plenty of food year round.
While some people object to GMO foods on the grounds that the long-term effects from eating them are unknown, probably the more salient argument is the effect they might have on the natural world. A larger, faster growing species could put tremendous pressure on already stressed, wild Atlantic salmon. AquaBounty counters that in normal ocean temperatures, the GMO salmon would grow no faster than wild salmon. Also, all of the GMO salmon are female, and 95 to 99% of them are sterile (they can’t reproduce). And none of that should matter, because the salmon will be raised in tanks, away from the ocean.
Even if they are successfully isolated from wild salmon, opponents point out, that doesn’t mean they are isolated from the environment. See, salmon eat other fish, and it takes about 2 pounds of other fish to make one pound of salmon (according to this article on the GMO salmon). Large amounts of the kinds of fish people don’t eat are caught and processed to feed farm-raised salmon. If cheaper, fast-growing salmon cause the demand for salmon to rise, more food stock fish will have to be caught to supply the farms, putting pressure on these other species.
A salmon farm: Nets keep the salmon in and the predators out, but disease, parasites, and pollution move through freely. But salmon farms reduce stress on wild salmon populations. It's complicated...Courtesy Dark jedi requiemThen again, if the GMO salmon can be raised successfully and profitably in inland tanks, it could remove other negative environmental impacts. Aquaculture fish farms are typically in larger bodies of water, with the fish contained inside a ring of nets. The high concentration of fish in one area leads to more diseases and parasites, which can spread to nearby wild fish. Salmon farms also produce lots of waste, and it’s all concentrated in one spot. Supposedly, a farm of 200,000 salmon produces more fecal waste than a city of 60,000 people. (That’s what they say—it sounds like a load of crap to me, though.)
It’s a tricky subject, and anyone who says otherwise is being tricky (ironically). Nonetheless, it seems likely that the Food and Drug Administration will soon declare this particular GMO as officially safe to eat, and GMO salmon fillets could make their way to the supermarket in the next couple years. Even if the FDA didn’t approve the fish, however, that would only mean that it couldn’t be sold in the US—the operation could continue to produce fish for international markets.
GMO salmon are just the tip of the GMO animal iceberg (if you’ll forgive the iceberg analogy—I don’t mean to imply that they are going to sink us.) The next GMO in line for FDA approval, probably, is the so-called “enviropig,” a GMO pig with a greater capability to digest phosphorus. This should reduce feed costs, and significantly lower the phosphorus content of the manure produced by the pigs. That’s important because phosphorus from manure often leaches into bodies of water, fertilizing microorganisms, which, in turn, reproduce in massive numbers and suffocate other aquatic life.
As the human population grows and needs more food, genetically engineered plants and animals are going to become increasingly common. They might make the process of feeding and clothing ourselves easier and more sustainable. Or they might royally screw things up. Or both. So start thinking about these things, and start thinking about them carefully.
Er… so what do you think about GMOs? Are they a good idea? Are they a good idea for certain applications? Are they a bad idea? Why? Scroll down to the comments section, and let’s have it!
IllustrationCourtesy José-Manuel Benitos via Wikimedia CommonsFossil bones of two hominins
found in a cave in South Africa, could be those of a completely new species of human and fill in a gap in human ancestry. The remains, which were found within a yard of each other, are of an adult middle-aged female and juvenile male. Scientists speculate the two could even be a mother and its child, or at least members of the same tribe. Either way, they add valuable information to the very fragmentary record of human evolution.
Professor Lee Berger, lead researcher of the discovery, and a paleoanthropologist at the University of the Witwatersrand, says the remains are well preserved and between the two of them include a nearly complete skull, shoulder, arm, lower leg, and hand. The pelvis is well represented, too. The fossils were found in the Malapa cave not far from the Cradle of Humankind World Heritage Site near Johannesburg.
Named Australopithecus sediba, the new finds which are nearly two million years old, have characteristics common to both Homo (which includes us) and Australopithecus, early ape-like creatures, making it an important transitional fossil between the two genera. Photo link
“That period between 1.8 and just over two million years - is one of the most poorly represented in the entire early hominid fossil record. You're talking about a very small, very fragmentary record," said," lead scientist Lee Berger. "It's at the point where we transition from an ape that walks on two legs to, effectively, us.”
Berger is a professor of paleoanthropology at the University of the Witwatersrand in Johannesburg. First evidence of the find was actually found by his 9 year-old son, Matthew, who picked up a couple fossils bones, a collarbone and jawbone that had been discarded by miners. Further investigation led to the rest of the remains. Professor Berger had found the cave in 2008 using Google Earth.
Although clearly australopithecine in size and stature, and most closely similar to the species Australopithecus afarensis, the boy’s skull and jaw also contain features seen in the genus Homo, such as the facial structure (e.g. a slight bony chin), and the shape and size of the premolars and molars. The two creatures upper limbs were overly long, again a trait of Australopithecus, and means they were more-than-likely arboreal, and able to easily climb trees to seek refuge and food. But their pelvic structures share features found in the hips of the Homo genus, leaning toward more efficiency in walking or running. This means A. sediba fills in some of the gap between Australopithecus afarensis and Homo erectus. Professor Berger’s study appears in the journal Science.
Berger suspects the two A. sediba had been swept into the cave by a flash flood or some such disaster and buried fairly quickly. The dig site produced the remains of 25 other animals such as a horse, saber-toothed cat, wild dogs, and antelope. None of the remains appear to have been scavenged Fossils from two other hominid individuals were also found but have not yet studied.
LINKS
Article at Science.
Video at Science
Podcast at Science
More pictures at NatGeo
Painting a new picture of human evolution: A finger bone found in a cave in southern Siberia may add another species to human evolution. (Painting by Charles R. Knight, AMNH).Courtesy Mark RyanThe bone of a single pinky finger found in a cave in southern Siberia may indicate a new branch in the human family tree. The find could show that besides Neanderthals and Homo sapiens, a third lineage of humans may have shared the ancient landscape of prehistoric Russia.
The piece of finger was found in Denisova cave located in Russia’s Altai mountains by scientists from the Russian Academy of Science. The bone was recovered from sediment layers that have also yielded signs of Neanderthals (Homo neanderthalensis) and modern humans (Homo sapiens). Radiocarbon dating set the age of the layers between 48,000 and 30,000 years old.
Scientists from Germany’s Max Planck Institute and others sequenced 16,569 base pairs of the finger bone’s mitochondrial DNA genome, and the results indicate the new hominen shared a common ancestor with both neanderthals and ancient modern humans sometime around a million years ago. The research team included Michael Shunkov and Anatoli Derevianko, the two Russian archaeologists who discovered the bone in 2008. The study appears in the journal Nature.
Further sequencing of DNA from cell nucleuses will be done next, and could help pinpoint the hominen’s exact origins. If confirmed, the discovery would mean four different species of humans (the 4th would be the Indonesian Hobbit Homo floresiensis) co-existed on Earth some 40,000 years ago.
SOURCE and LINKS
Science Now story
More about human evolution at Becoming Human
Radiocarbon dating
