Evolution


The human Y chromosome has retained only 3% of its ancestral genes. So why is it a shadow of its former self? Rafael Anderson Gonzales Mendoza/Flickr, CC BY-NC-SA

By Jenny Graves, La Trobe University

The Y chromosome, that little chain of genes that determines the sex of humans, is not as tough as you might think. In fact, if we look at the Y chromosome over the course of our evolution we’ve seen it shrink at an alarming rate.


The bobtail squid and bioluminscent bacteria are just one of hundreds of examples of mutualism. Klaus Stiefel/Flickr, CC BY-NC

By Alex Jordan, University of Texas at Austin

The 1KITE project (1,000 Insect Transcriptome Evolution) seeks to understand the millions of living insect species that shape our terrestrial living space and both support and threaten our natural resources by analyzing more than 1,000 insect transcriptomes, a set of all RNA molecules.

Using a dataset consisting of 144 carefully chosen species, 1KITE scientists have just presented reliable estimates on the dates of origin and relationships of all major insect groups based on the enormous molecular dataset they collected. They show that insects originated at the same time as the earliest terrestrial plants about 480 million years ago.
8 percent of our genome derives from retroviruses that inserted themselves into human sex cells millions of years ago and right now the koala retrovirus (KoRV) is invading koala genomes.

Koalas are the only known organism where a retrovirus is transitioning from exogenous to endogenous. An exogenous retrovirus infects a host, inserts its genetic information into the cell’s DNA, and uses the host cell’s machinery to manufacture more viruses. When an exogenous retrovirus infects an egg or sperm cell and the viral genetic information is then passed down to the host’s offspring, the virus becomes an endogenous retrovirus (ERV). 

Scientists believe that Eurasians separated into at least three populations around 36,000 years ago: Europeans,Asians and a mystery third lineage, all whose descendants would develop the unique features of most non-African peoples after interbreeding with Neanderthals. 

A new study on DNA recovered from a fossil of one of the earliest known Europeans, who lived 36,000 years ago in Kostenki, western Russia, has shown that the earliest European humans' genetic ancestry survived the Last Glacial Maximum - the peak point of the last ice age. 


Nature enjoys variety, that is why it seems like evolution must have been drinking during the creation of some of the crazier things in biology. 

There is no intelligent reason why snakes and lizards have two genitalia while birds and people have one - or why the former group's paired structures are located somewhat at the level of the limbs while with humans and birds it appears a bit further down. In fact, snake and lizard genitalia are derived from tissue that gives rise to hind legs, while mammalian genitalia are derived from the tail bud. But despite such noteworthy contrasts, these structures are functionally analogous and express similar genes. 

How do these equivalent structures arise from different starting tissues? 


Biology can be inspirational.  The spiral ramps in multistory parking garages, the way they are stacked and connecting parallel levels, are replications of helical structures found in a ubiquitous membrane structure in the cells of the body - Terasaki ramps in an organelle called the endoplasmic reticulum (ER), a network of membranes found throughout the cell and connected to and surrounding the cell nucleus.

A team of researchers have described endoplasmic reticulum geometry using the language of theoretical physics in Physical Review Letters.



By Sarah King, Genetic Literacy Project

Since the discovery in 2004 of Homo floresiensis, an ancient hominid nicknamed “Flo” and also “hobbit”, after the diminutive villagers from J.R.R. Tolkien’s Lord of the Rings trilogy, due to her small size relative to modern humans, much debate has been raised over the origins of the species.

Scientists have documented the rapid evolution of a native lizard species as a result of pressure from an invading lizard species introduced from Cuba. 

After contact with the invasive species, the native lizards began perching higher in trees, and, generation after generation, their feet evolved to become better at gripping the thinner, smoother branches found higher up. It only took about 20 generations - 15 years - but even within a few months, native lizards had begun shifting to higher perches and as time passed their toe pads had become larger, with more sticky scales on their feet.


Though Ebola tends to occur in waves, the filoviruses family to which Ebola and its lethal relative Marburg belong, are at least 16 million years old.

Filoviruses likely existed in the Miocene Epoch, and at that time, the evolutionary lines leading to Ebola and Marburg had already diverged, according to a paper inl PeerJ. It was once believed that the viruses only came into being some 10,000 years ago, coinciding with the rise of agriculture but now it is believed to have developed at the time when great apes arose.