I really enjoyed reading these articles:
Convergent Evolution in Poison Frogs
“Scientists have discovered one of the most intricate examples of convergent evolution with the help of South American “poison” frogs and ants and their cousins in Madagascar. (And hereâ€™s an odd fact for smokers: one Madagascan frog studied was found to have nicotine in its system!)
Poison frogs canâ€™t make their own poisonâ€”they steal it from ants. Poison frogs secrete a variety of chemicals called alkaloids to create a poisonous defense against predators. Since they canâ€™t produce alkaloids on their own, these frogs maintain a steady diet of specific alkaloid-rich ants to keep up their defense.
Now, Valerie Clark of Cornell University and her colleagues have detailed two instances of convergent evolutionâ€”the process in which organisms not closely related independently acquire similar characteristics while evolving in separate ecosystemsâ€”between frogs and ants on two continents.
First, species of ants high in alkaloids had to evolve on two separate continents.
“The ants had to be there with alkaloids for the frogs to evolve to get alkaloids in their skin,” Clark told LiveScience.
Then the frogs had to develop a resistance to the alkaloidsâ€”instead of spitting out the ants or passing the alkaloids through their systems, the frogs became able to keep their ant dinners down. Then they evolved to make use of the alkaloids themselves.
Also, both the frogs in South America and Madagascar evolved to have “donâ€™t-eat-me” skin colorings, the final step in a remarkable tale of multi-step convergent evolution.
Up until now, scientists have mainly studied frogs from South America and Australia. But Clark and her colleagues showed that the Madagascan frogs needed the same types of food to be poisonous.
They examined the stomach contents of 21 frogs from the genus Mantella and found that alkaloid rich ants made up 67 percent of their food intake.
Not only that, but they found nicotineâ€”the same chemical found in cigarettesâ€”in one Mantella baroni frog out of 22 examined. Nicotine is produced by plants and can sometimes be found in animals that eat these plants. But so far no nicotine-producing plants have been found growing in the area where this frog was found. This was the first time researchers observed this phenomena and they are not sure how the chemical enters the frogâ€™s system.”
At a physics meeting last October, Nobel laureate David Gross outlined 25 questions in science that he thought physics might help answer. Nestled among queries about black holes and the nature of dark matter and dark energy were questions that wandered beyond the traditional bounds of physics to venture into areas typically associated with the life sciences.
One of the Gross’s questions involved human consciousness.
He wondered whether scientists would ever be able to measure the onset consciousness in infants and speculated that consciousness might be similar to what physicists call a “phase transition,” an abrupt and sudden large-scale transformation resulting from several microscopic changes. The emergence of superconductivity in certain metals when cooled below a critical temperature is an example of a phase transition.
In a recent email interview, Gross said he figures there are probably many different levels of consciousness, but he believes that language is a crucial factor distinguishing the human variety from that of animals.
Gross isn’t the only physicist with ideas about consciousness.
Beyond the mystics
Roger Penrose, a mathematical physicist at Oxford University, believes that if a “theory of everything” is ever developed in physics to explain all the known phenomena in the universe, it should at least partially account for consciousness.
Penrose also believes that quantum mechanics, the rules governing the physical world at the subatomic level, might play an important role in consciousness.
It wasn’t that long ago that the study of consciousness was considered to be too abstract, too subjective or too difficult to study scientifically. But in recent years, it has emerged as one of the hottest new fields in biology, similar to string theory in physics or the search for extraterrestrial life in astronomy.
No longer the sole purview of philosophers and mystics, consciousness is now attracting the attention of scientists from across a variety of different fields, each, it seems, with their own theories about what consciousness is and how it arises from the brain.
In many religions, consciousness is closely tied to the ancient notion of the soul, the idea that in each of us, there exists an immaterial essence that survives death and perhaps even predates birth. It was believed that the soul was what allowed us to think and feel, remember and reason.
Our personality, our individuality and our humanity were all believed to originate from the soul.
Nowadays, these things are generally attributed to physical processes in the brain, but exactly how chemical and electrical signals between trillions of brain cells called neurons are transformed into thoughts, emotions and a sense of self is still unknown.
“Almost everyone agrees that there will be very strong correlations between what’s in the brain and consciousness,” says David Chalmers, a philosophy professor and Director of the Center for Consciousness at the Australian National University. “The question is what kind of explanation that will give you. We want more than correlation, we want explanation — how and why do brain process give rise to consciousness? That’s the big mystery.”