Posts tagged evolution
Articles and news from the latest research reports.
Compelling evidence that brain parts evolve independently
An evolutionary biologist at The University of Manchester, working with scientists in the United States, has found compelling evidence that parts of the brain can evolve independently from each other. It’s hoped the findings will significantly advance our understanding of the brain.
The unique 15-year study with researchers at the University of Tennessee and Harvard Medical School also identified several genetic loci that control the size of different brain parts.
The aim of the research was to find out if different parts of the brain can respond independently of each other to evolutionary stimulus (mosaic evolution) or whether the brain responds as a whole (concerted evolution). Unlike previous studies the researchers compared the brain measurements within just one species. The findings have been published in the journal Nature Communications.
The brains of approximately 10,000 mice were analysed. Seven individual parts of each brain were measured by volume and weight. The entire genome, except the Y chromosome, was scanned for each animal and the gene set for each brain part identified.
Dr Reinmar Hager from the Faculty of Life Sciences compared variation in the size of the brain parts to variation in the genes. He found that the variation in the size of brain parts is controlled by the specific gene set for that brain part and not a shared set of genes.
He also compared the measurements for each mouse to the overall size of its brain. Surprisingly he found very little correlation between the sizes of the brain parts and the overall size of the brain.
Dr Hager says: “If all the different brain parts evolved as a whole we would expect that the same set of genes influences size in all parts. However, we found many gene variations for each different part of the brain supporting a mosaic scenario of brain evolution. We also found very little correlation between the size of the brain parts and the overall size of the brain. This again supports the mosaic evolutionary hypothesis.”
Using the data collected from the mice Dr Hager and colleagues analysed the genes that influence the size of the brain to the genes that control the size of the body. They wanted to find out how independent size regulation of the brain is to that of the body.
They found evidence that the size of the brain is governed by an independent gene set to the one that controls the size of the body. Again they found vey little correlation between variations in the size of the body and the brain.
The evidence means that overall brain size can evolve independently of body size.
Following this research more work will be carried out to identify the specific genes that underlie the size of different parts in the brain
Dr Hager says: “If we can identify the specific genes that cause variations in the size of brain parts then there will be big implications for researchers looking at neuronal disease and brain development. We hope this research will significantly advance our understanding of the brain.”
(Source: manchester.ac.uk)
New Caledonian crows reason about hidden causal agents
We have generally believed that animals are not capable of very complex thought, even though many species use tools and engage in other complex behaviors.
Even a bird brain appears to be capable of understanding things that are not visible may be affecting their environment.
This study looks at whether New Caledonian crows, that were caught just for this experiment, are capable of attributing actions to a hidden cause, when they see that possible cause come and go.
How do language families evolve over many thousands of years? How stable over time are structural features of languages? Dan Dediu and Stephen Levinson from the Max Planck Institute for Psycholingustics in Nijmegen introduced a new method using Bayesian phylogenetic approaches to analyse the evolution of structural features in more than 50 language families. Their paper ‘Abstract profiles of structural stability point to universal tendencies, family-specific factors, and ancient connections between languages’ was published online on September 20, 2012 in PLoS ONE.
A new study, published online in Biology Letters on September 19, has utilized a massive molecular dataset to reconstruct the evolutionary history of lizards and snakes. The results reveal a surprising finding about the evolution of snakes: that most snakes we see living on the surface today arose from ancestors that lived underground.
(Source: newswise.com)
A glance at a star-nosed mole (Condylura cristata) is enough to convince most people that something very strange has evolved in the bogs and wetlands of North America. There’s nothing else on the planet quite like this little palm-sized mammal. Its nose is ringed by 22 fleshy appendages, called rays, which are engorged with blood and in a constant flurry of motion when the animal searches for food.
What is this star? How did it evolve and what is it for? What advantage would be worth sporting such an ungainly structure? To a neuroscientist interested in sensory systems, this kind of biological anomaly represents an irresistible mystery. I first began studying star-nosed moles in the early ’90s in an attempt to answer some of these basic questions. But I soon discovered that this unusual animal, like many other specialized species, could reveal general principles about how brains process and represent sensory information. In fact, star-nosed moles have been a gold mine for discoveries about brains and behavior in general—and an unending source of surprises. The most obvious place to start the investigation was with that bizarre star.
(Source: the-scientist.com)
What good is color vision in the dark of the deep sea? For some crabs, an ability to see blue and ultraviolet light may mean the difference between chowing down on a good meal versus a toxic one.
A new study published in the Journal of Experimental Biology finds that some seafloor, or benthic, crabs can see in color. But the crustaceans live in darkness of the deep Caribbean where sunlight does not penetrate, making their sensitivity to blue and ultraviolet light mysterious.
(Source: livescience.com)
High quality Denisovan genome sheds light on human evolution: Sequencing our extinct relatives let us know how we differ from chimps.
The discovery that a second branch of the human family shared Asia with our ancestors and the Neanderthals was a real shock, but the Denisovans have continued to surprise many. All we have of them is a bit of a finger and some molars, but those few fragments have yielded a wealth of DNA, and with it the knowledge that the Denisovans interbred with the ancestors of some modern human populations. Now, with the help of a new approach to sequencing ancient DNA, we actually know more about the Denisovans’ genome than we do about Neanderthals’. In the process, we’ve discovered some of the changes that are distinct to modern humans.
The connections between the rising rates of chronic disease and the production and consumption of modern foods can no longer be ignored. Our food supply is not healthy, nor is it sustainable. It has changed so dramatically that we have yet to adapt to the changes. Our food supply has been completely adulterated over the past few decades alone, more drastically than during any other time in history.
Baby songbirds learn to sing by imitation, just as human babies do. So researchers at Harvard and Utrecht University, in the Netherlands, have been studying the brains of zebra finches—red-beaked, white-breasted songbirds—for clues to how young birds and human infants learn vocalization on a neuronal level.
While a baby bird mimicking the chirps of his “tutor” may seem far removed from human learning, the researchers at the two universities found that the songs of the birds and human language are both processed in similar areas on the left sides of the two very different brains. The discovery was published last month in the Proceedings of the National Academy of Sciences.
Early fruits of the collaboration between the Genome 10K project and Beijing Genomics Institute (BGI) to sequence 100 vertebrate species have resulted in the sequencing and release of the genome of one of naturalist Charles Darwin’s Galápagos finches, the medium ground finch Geospiza fortis.
This finch genome, the first of the BGI-Genome 10K collaboration to be made available through the UCSC Genome Browser, represents both a scientific and a symbolic advancement, according to Erich Jarvis, Duke University associate professor who studies the neurobiology of vocal learning in songbirds.
Endemic to the subtropical or tropical dry forests and shrublands of the Galápagos Islands this species evolves rapidly in response to environmental changes. ”These finches are of great historical significance, but when Darwin first studied these birds, he was unlikely to have envisioned how this species would become a perfect model to study evolution in action,” said Goujie Zhang, BGI’s associate director of research. “Having the reference genome of this species has opened the door for carrying out studies that can look at real-time evolutionary changes on a genomic level of all of these enigmatic species.”
(Image by: Petr Baum)