Annalee Newitz - Are Humans on the Verge of Evolving into Another Species

This is an interesting article - a look at the process of speciation. The implication seems to be that those species with brains that rapidly adapt by increasing sensory processing are more likely to evolve into new species. Is social networking - and the supposed ADD that results - spurring potential human evolution? Maybe. Probably not soon, though.

The first sign that humans are on the verge of evolving into another species

Annalee Newitz — A scientist who studies the small, silver elephantfish may have stumbled on the key to speciation, the process that allows one species to evolve into two or more. And it's all about developing new sensory perceptions.

The elephantfish, like a few other creatures who live in cloudy water, communicates via weak electrical signals. Using a special organ that sends and receives the signals, the fish are able to navigate and find each other even when there is zero visibility. Washington University biologist Bruce Carlson has studied roughly 200 species of these fish for many years, and wanted to find out if there was any connection between the structure of the fishes' brains and their rapid speciation. What he found was that brain complexity seemed to cause fish to evolve and diversify quickly. And the brain complexity came directly from the fishes' sensory processing power.

According to a release about the study:

Living in clouded, muddy environments requires the fish to recognize the electrical signals of their own species and ignore signals from other species. With that in mind, the researchers looked at a region of the midbrain that is devoted to analyzing such signals, known as the exterolateral nucleus or EL, in 26 different species of elephant fishes. They found that EL development led to improved signal detection and rapid speciation in one lineage of Mormyrids, while a sister lineage that diverged prior to EL development had reduced signal detection abilities and has not diversified.

The fish that were better able to recognize different kinds of electrical discharges and pulses, as well as the timing of pulses, had far more complex sensory systems than the ones that didn't.

At left, you can see an illustration of the different species. Carlson and his colleagues write today in Science:

In the top group of fishes, species in the genus Paramoryrops that has the complex signal-processing brain, discharges have changed quickly, resulting in dramatically different pulses among closely related species. In the bottom group of fishes, species in the genus Petrocephalus whose midbrain is more simply structured, all of the species have similar pulses. The difference arises because the top group has the anatomical features needed to exploit the signal space — such as the anatomy needed to make different pulses and the sensory and analytical ability to perceive small differences in pulse shape.

Said Carlson:

It's always difficult with evolutionary studies to say that any one trait is the cause or the trigger for another. But in this case we were able to show that the complex signal-processing brain evolved before a burst of speciation, that signal variation was higher among fishes with that brain, and that these fishes could distinguish among subtly different pulses, whereas others could not. Together it adds up to a strong case for brain evolution triggering increased diversification.

What Carlson's work suggests is that species whose brains are evolving fairly rapidly - hello, Homo sapiens - are likely candidates for speciation under the right circumstances. The key with the elephantfish seemed to be rapid evolution in the brain's ability to sort out sensory inputs.

Does that mean that as humans deal with more sensory bombardment from our mediascape that we'll start evolving into multiple species? Perhaps humans who live in low-sensory bombardment areas in rural regions will remain Homo sapiens while the rest of us become weird new creatures who are able to navigate narrow streets covered in augmented reality overlays? Let the rank speculation begin.

Read the full scientific paper via Science.

Illustration by imredesiuk/Shutterstock

The full paper is pay-walled, so here is the abstract:

Brain Evolution Triggers Increased Diversification of Electric Fishes

1. Bruce A. Carlson¹,*,
2. Saad M. Hasan¹,
3. Michael Hollmann¹,
4. Derek B. Miller¹,
5. Luke J. Harmon², and
6. Matthew E. Arnegard³

+ Author Affiliations

1. ¹Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA.
2. ²Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA.
3. ³Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.

1. *↵To whom correspondence should be addressed. E-mail: carlson.bruce@wustl.edu

Abstract

Communication can contribute to the evolution of biodiversity by promoting speciation and reinforcing reproductive isolation between existing species. The evolution of species-specific signals depends on the ability of individuals to detect signal variation, which in turn relies on the capability of the brain to process signal information. Here, we show that evolutionary change in a region of the brain devoted to the analysis of communication signals in mormyrid electric fishes improved detection of subtle signal variation and resulted in enhanced rates of signal evolution and species diversification. These results show that neural innovations can drive the diversification of signals and promote speciation.

Tags: humans, evolution, brain, senses, Annalee Newitz, io9, Human beings, on the Verge, Evolving, new Species, speciation, elephantfish, Bruce Carlson, complex sensory systems