In which context did life arise? A problem yet unsolved. Several plausible ideas and hypotheses have been put forward: shallow seas, meteorites (see DNA, Made In Space?), and even much more extreme habitats, such as hydrothermal vents. Perhaps pumice should be added to the list?

Pumice (see figure 1), a volcanic rock formed by solidified frothy lava, is known to be porous and, once upon a time in its history, gas-rich. Now, a new study, published in Astrobiology, poses that extensive rafts of pumice have four properties that would actually make them a suitable candidate for the location where life arose.

A new study in Nature shows that genetic parasites invaded the mammalian genome more than 100 million years ago and dramatically changed the way mammals reproduce.

The molecular changes allowed mammals to carry their developing young within the womb rather than laying them in nests or carrying them around in pouches - the uterus was transformed. 

The findings published online Sept. 25 in the journal Nature Genetics describe in unprecedented detail the molecular changes that allowed mammals to carry their developing young within the safety of the womb rather than laying them in nests or carrying them around in pouches.

In a protein coding sequence of DNA, three subsequent nucleotides form codons (see figure 1), which, in turn, form amino acids that will eventually give rise to a protein. Some of these codons, however, are synonymous, meaning that one amino acid can be encoded by several different codons. When an amino acid is preferentially encoded by one of several potential synonymous codons, it is called codon bias.

   

Figure 1: Example of a codon. (GCA codes for alanine, which is also encoded by the synonymous codons GCT, GCT and GCG.)

(Source: Georgia Southern University, Department of Biology.)

   

New research that includes representatives of 99% of mammalian families, has provided a ‘big picture’ for mammalian phylogeny. By assembling a large and robust DNA matrix, based on sequences of many different genes, a research team led by biologists from the University of California, Riverside and Texas A&M, has examined how different families are related to each other.

A hot new study in Nature has rearranged the molluscan family tree--with some surprising results!

No one can deny that cephalopods (squids, octos, and cuttles) are the brains of the family, with their cousins the gastropods (slugs and snails) coming in a close second. We'd all assumed that these two groups were closely related, with cephalopods evolving from a gastropod-like ancestor, refining a brain that already existed.

However! As summarized in the New Scientist:

Tuesday evening, Facebook made major changes to its news feed and today the Internet is a hornet’s nest of complaints, protests, and threats. There is a new round of “quit Facebook” memes, and a collective groan of pain from millions of users. Similar dissent occurred when Netflix recently spun off its DVD-by-mail service into a separate company, Qwikster, or earlier this year when dating site OKCupid was purchased by the behemoth Match.com.

We've often defended Jean-Baptiste Lamarck.  Publishing 50 years before Darwin, he can be forgiven for not having 'the greatest idea anyone ever had' and in the last few years,  geneticists have gotten on board as well and no longer dismiss out of hand his belief that acquired traits can be passed on to offspring.

Much of the pre-Darwin thinking was teleological and that is why natural selection in evolution met so much resistance.  But science quickly won and Lamarck's theory of transformation went onto the ash heap of biological history. Yet in the last decade, we have learned that the environment can leave traces in the genomes of animals and plants, in the form of epigenetic modifications.

What is life? As tough questions come, this is a good one. It seems simple at first, but even after great advances in biology and a sizeable increase in understanding how life works, there appears to be no real consensus on life. To quote Carl Sagan:

Sex determination is obviously an important developmental event with great ecological and evolutionary consequences. A large variety of sex determination mechanisms exists, and the evolution of many of these is still relatively poorly understood. Previous work suggests that compensatory adaptations to mutations in involved genes might be relevant in the evolution of these pathways.