Thursday, January 29, 2015

The mystery of the Cambrian explosion

550 million years ago, during the Cambrian period, animals appear suddenly in the fossil record. This spectacular phenomenon has been given the name of Cambrian explosion. Why did it happen then, and not before, has been, for over a century, one of the great mysteries of paleontology.
The evolution of life on Earth seems to have been rather discontinuous. Life is likely to have appeared 3,500 to 4,000 million years ago. Not much later, around 3,000 million years ago, photosynthesis appeared. Eukaryotes (cells with nuclei) emerged 2,000 million years ago. From then until the Cambrian explosion, nothing much seems to have happened for 1,500 million years. Then all the types of organization of the animals existing today appear suddenly. Why?

Thursday, January 22, 2015

The case of the hunting hymenoptera

Jean-Henri Fabre
In 1879, the French entomologist J. H. Fabre studied many species of hymenoptera (solitary wasps and bees) that hunt other insects as food for their larvae. This is the reason for their name (hunting hymenoptera, also called -improperly- parasite hymenoptera). Before laying the eggs, the hymenoptera paralyze the prey by injecting with their sting a drop of poison in every nerve ganglion in the un-centralized nervous system of the prey. In some species, such as Ammophila hirsuta, which hunts caterpillars, the number of ganglions may be large (up to twelve, one per segment in the caterpillar). The hunter seems to know where exactly its prey must be stabbed with the sting.
Once the prey has been paralyzed and the egg laid, the minute larva of the hymenopter digs inside the prey and starts devouring it, showing an apparent innate knowledge of the prey anatomy: it starts feeding on the parts less necessary for life, leaving the vital organs to the last. In this way, the prey does not die and rot, which would make it improper as food and lead to the death of the predator.
Ammophila sabulosa carrying a hunted caterpillar

Thursday, January 15, 2015

About religious and thought intolerance

A photo-gram in film Intolerance (1916)
We can hear frequently people stating that cultures and civilizations in ancient times were respectful and tolerant with other religions, in such a way that all beliefs lived together in peace and harmony. This turned to religious intolerance and religious wars when monotheistic religions (Judaism, Christianity and Islam) dominated a great part of the world during the latest 2000 years.
The supposed tolerance of paganism has prevailed as a myth in our modern mindset, but is not true. To see it, we should remember that all the wars in pagan countries (Egyptians against Hittites, Assyrians against Syrians, Babylonians and Egyptians, and so forth) were always considered as conflicts between their gods. The victors attributed their victory to their own gods, and felt a religious right to act cruelly against the losers. Just remember the pyramids the Assyrians built when they conquered a city with the heads of all the men and boys living there; women and small children were just deported as slaves. Or just remember that the death sentence against Socrates was really a case of religious persecution, for he was incorrectly accused of teaching atheism to the youth.

Thursday, January 8, 2015

Anthropic and supranthropic properties

In a previous post I wrote about the fine tuning problem, based on the verification that many of the properties of the universe seem designed to make our existence possible. In other words: those properties verify the anthropic principle, another way of saying that the universe must fulfill all the conditions needed for our existence, since we are here. On the other hand, the mediocrity principle states that the anthropic conditions of the universe should be the necessary minimum to make our existence possible.
Robin James Spivey has lately published a book titled Aqueous solution, where he asserts that certain properties of the cosmos are supranthropic (they go beyond the anthropic principle) because they are not required for our existence, but their presence guarantees our long-range survival. According to Spivey, those properties are an inkling of design stronger than the anthropic properties, as the mediocrity principle opposes their presence.

Thursday, January 1, 2015

The chaos of copyright rules

When publishers and author associations complain about the huge amount of copyright violation in piratical download of digital publications, including electronic books (e-books), they should start by trying to put a little order in the chaos of copyright laws, which has become outstanding since Internet has made easy the exchange of digital files between world-wide users. Let us consider a few examples of this chaos:
·         In the USA, every book published before 1923 is in the public domain. For those published between 1923 and 1963, the default duration was 28 years after publication, which could be extended to 95 by renewing the copyright. The latter became the copyright duration for all books between 1964 and 1977. After 1978, copyright expires 70 years after the author’s death.