8 Feruary 2011: Genes Older Than Earth? What'sNEW

Rates of macroevolutionary events over time: "Average rates of gene birth (red), duplication (blue), HGT (green), and loss (yellow) per lineage (events per 10 Myr per lineage).... Events that increase gene count are plotted to the right, and gene loss events are shown to the left." (The horizontal blue line at 2.4 billion years ago was added.) — adapted from David & Alm, 2011	"...The inset shows metabolites or classes of metabolites ordered according to the number of gene families that use them that were born during the Archaean Expansion compared with the number born before the expansion, plotted on a log2 scale...."

The birth rate peaked sharply at the beginning of the period (as indicated in the figure by a red spike pointing right). The rate of gene loss also reached a maximum during this time, peaking at about 3.1 billion years ago (fat yellow arm pointing left). The analysis also measures HGT (green) and gene duplication (blue). Curious to know where genes come from, we focus on the births.

If life descends from a single Earthly ancestor, one would expect the red graph of gene births to descend from a single point, broadening as life spreads over the planet, then becoming more-or-less constant as life continues to evolve. Instead, this graph begins as a broad front that soon widens dramatically. Then it narrows more dramatically and eventually dwindles to nothing, well before the Cambrian Explosion of about 540 million years ago (indicated by lower dashed line in figure.)

"...Genes that use molecular oxygen are more likely to appear in organisms that emerged after the Great Oxidation Event," indicated at its consensus starting time of 2.4 billion years ago by a horizontal blue line added to the main graph above. Yet many oxygen-using genes were born much earlier, during the Archaean Expansion. In fact, their birth rate was apparently enriched then (as indicated in inset by blue bars pointing right). This makes no darwinian sense. David and Alm wonder if the oxygen-related genes may have served another purpose originally.

The initial front would be even broader if David and Alm had not omitted the genes that are the most widely distributed of all. "Genes already present at the Last Universal Common Ancestor are not included in the analysis of birth rates because the time over which those genes formed is not known." Yes, because they were already formed before the graph begins! The research team also omitted "ORFan gene families (gene families found in only a single genome), which are widespread across all major prokaryotic groups...." They think these may have been born relatively recently, because evidence for them long ago is rare. Or, is that evidence just easily missed?

Another point needs making. The term "birth" implies a process that might include gestation — the gradual composition of new genes by darwinian mutation-and-selection. But not a bit of it. No such process is claimed to be observed here. Gene "birth" refers only to the latest plausible time when a given gene might have become available for expression, proliferation and divergence among (mostly prokaryotic) species. And since genes may go unexpressed for millions of years, all of the studied genes may have existed long before they were "born" in this study.

In cosmology, at least two groups now claim that the evidence (microwave background radiation) enables them to see beyond (before) the big bang. We suggest that an analogous phenomenon may be possible in biology. Here David and Alm show that many genes were available at the very beginning of life on Earth, and that many more genes apparently preceded the earthly advent of the features they encode. Other studies provide corroborating data. Could all of this be evidence for life older than Earth? We think so.

What'sNEW

2 Nov 2011: Almost every month now we are seeing genes that were supposed to be exclusive to metazoans that are already present in their single-cell relatives.
7 Oct 2011: The protein was there to begin with.... — Gustavo Caetano-Anollés, University of Illinois.
12 Jul 2011: Genetic instructions for developing limbs and digits were present in primitive fish millions of years before their descendants first crawled on to land....
18 Jun 2011: ...The tool kit for more complex plant architectures was already in place long before angiosperms evolved.
26 May 2011: The common ancestor of life on Earth had more functional protein domains than the first cells!
13 May 2011: Many scientists now argue that viruses contain a genetic archive that's been circulating the planet for billions of years.
Dr. Doron Golberg asks for clarification, 10 Feb 2011.
27 Jan 2011: This webpage was first posted as a What'sNEW article titled "Many genes were 'born' on Earth much earlier than expected by mainstream theory".

abstract], doi:10.1038/nature09649, p93-96 v469, Nature, 6 Jan 2011 (online 19 Dec 2010); and a press release, Scientists decipher 3 billion-year-old genomic fossils by Denise Brehm, MIT News Office, 19 Dec 2010.
Metazoan Genes Older Than Metazoa? is the main related local webpage, with examples of corroborating evidence.
Viruses and Other Gene Transfer Mechanisms is relevant. The above graph illustrates for HGT (green) the pattern darwinism would predict for gene "birth" — descending from a narrow beginning and broadening to a fairly constant rate.
How is it Possible? suggests that life might arrive with a wide range of capabilities, many of which are soon lost.