The latest findings support previous research showing the same correlation between brain size and metabolic rates among humans and their great ape relatives.
Author: gerrity
Why big brains are rare: Studies of electric fish show really big brains evolve only if energy intake goes up (Links to an external site)
As a species, we’re so brain-proud it doesn’t occur to most of us to ask whether a big brain has disadvantages as well as cognitive benefits.
“We can think of tons of benefits to a larger brain, but the other side of that is brain tissue is incredibly ‘expensive’ and increasing brain size comes at a heavy cost,” said Kimberley V. Sukhum, a graduate student in biology in Arts & Sciences at Washington University in St. Louis.
Why big brains are rare (Links to an external site)
Do big-brained creatures steal energy for their brains from other organs or eat more to supply this expensive tissue? New work in large-brained fish suggests skimping elsewhere is not enough to meet the energy demands of an extreme brain.
Why big brains are rare: Studies of electric fish support the idea that really big brains can evolve only if constraints on energy intake are lifted (Links to an external site)
Do big-brained creatures steal energy for them from other organs or eat more to supply this expensive tissue? New work in large-brained fish suggests skimping elsewhere is not enough to meet the energy demands of an extreme brain.
Really big brains can evolve only if constraints on energy intake are lifted (Links to an external site)
The mormyrids have a reputation as large-brained fish and indeed one species (the fish in the top photo) has a brain that constitutes 3 percent of its body size, comparable to human brains, which range from 2 to 2.5 percent. But it was unclear whether other mormyrids were equally brainy.
Why Big Brains Are Rare (Links to an external site)
Studies of electric fish support the idea that really big brains can evolve only if constraints on energy intake are lifted.
As a species we’re so brain-proud it doesn’t occur to most of us to ask whether a big brain has disadvantages as well as cognitive benefits.
“We can think of tons of benefits to a larger brain, but the other side of that is brain tissue is incredibly ‘expensive’ and increasing brain size comes at a heavy cost,” said Kimberley V. Sukhum, a graduate student in biology in Arts & Sciences at Washington University in St. Louis.
Move over Garmin: African fish species have their own built-in fish finders (Links to an external site)
A family of African fish known as mormyrids communicate through a unique series of electric discharges generated by an organ in their tails, and some of them can gather detailed information about the creature from which the signal originated from its waveform.
Fish talk to each other electrically
There are differences between species. The most sensitive can determine the signaler’s species, sex, age, relative dominance status, and possibly even individual identity. They can also detect emotional states, such as aggression, submission, courtship and active exploration. This was reported in Science in 2011, according to biologist Dr Bruce Carlson of Washington University in St. Louis, who […]
Fish that have their own fish finders: Weakly electric fish use oscillatory receptors to find their neighbors (Links to an external site)
The more than 200 species in the family Mormyridae communicate with one another in a way completely alien to our species: by means of electric discharges generated by an organ in their tails.
These fish talk to each other with electric tails (Links to an external site)
“If you’re solitary and territorial and you detect another fish in the area, you want to know exactly who that fish is. Is it a potential competitor, a potential mate, or a different species you’re not worried about,” says Bruce Carlson. “On the other hand, if you’re living in a shoal or school of fish, it’s not so important to identify individuals. Just sticking with the group is going to be a successful strategy.”
Fish that have their own fish finders (Links to an external site)
In a 2011 article in Science that described a group of mormyrids able to perceive subtle variations in the waveform of electric signals, Washington University in St. Louis biologist Bruce Carlson, PhD, noted that another group of mormyrids are much less discriminating.
Fish that have their own fish finders: Weakly electric fish use oscillatory receptors to find their neighbors (Links to an external site)
The fish with nuanced signal discrimination can glean a stunning amount of information from electric signals, including the signaler’s species, sex, age, relative dominance status, and possibly even individual identity. They can also detect emotional states, such as aggression, submission, courtship and active exploration.
Fish That Have Their Own Fish Finders (Links to an external site)
In the August 4 issues of the online journal eLIFE, Carlson and graduate student Christa Baker describe how they discovered the basis for the perceptual differences between the two groups of fish by studying the fish’s sensory receptors.
Congratulations Dr. Christa Baker
Dr. Christa Baker defended her PhD and is now a postdoc with Dr. Mala Murthy at Princeton, and was awarded fellowships from NSF and the Jane Coffin Childs Memorial Fund for Medical Research.
Listen to an Interview with Bruce on the “People Behind the Science” podcast (Links to an external site)
008: Dr. Bruce Carlson: Shocking Research with Mildly Electric Fish
Electric eels generate enough juice to power 10 lightbulbs (Links to an external site)
SPECIAL ISSUE: Electric fishes: neural systems, behaviour and evolution (Links to an external site)
Guest editors: Rüdiger Krahe and Eric Fortune. Including: Multiplexed temporal coding of electric communication signals in mormyrid fishes Christa A. Baker, Tsunehiko Kohashi, Ariel M. Lyons-Warren, Xiaofeng Ma, Bruce A. Carlson
Jennifer Stevens wins 2013 Spector Prize (Links to an external site)
The Spector Prize, first awarded in 1974, recognizes academic excellence and outstanding undergraduate achievement in research. Students are nominated by their research mentors for outstanding research that has made substantial contributions to a field.
Mechanisms of Signal Diversity in Communication (Links to an external site)
All of the fish pictured here are in the family Mormyridae and can produce and sense electric fields. In the top group of fish (subfamily Mormyrinae), electric discharges have evolved quickly, resulting in dramatically different pulses of electricity among closely related species. In the bottom group of fish (subfamily Petrocephalinae), 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.
Can You Feel Me Now? (Links to an external site)
While studying the distinctive patterns of discharges from African electrical fish, Carlson et al. (p. 583) discovered that the evolution of key sensory processing regions in the brain allowed for rapid diversification in one group but was minimal in a closely related group that had diverged prior to the evolution of the sensory innovations.