Thursday, April 19, 2018

The end of the selfish gene

The German biologist August Weismann (1834-1914) was one of the most influential biologists of the late nineteenth century. His most important contribution was the theory of germinal plasma, also called in his honor Weismannism. According to this theory, there are two classes of cells in all multi-cellular living organisms (see Figure 1):
Figure 1
  • Somatic cells, represented in the figure by an S, that make up most of the body and do not play any role in inheritance.
  • Germ cells, represented in the figure by a G: the gametes, ovules and sperm, which pass the genetic information to the next generation.

Thursday, April 12, 2018

Epigenesis and epigenetics

Fertilization of the egg by the sperm
In the previous post we saw that at the beginning of the 19th century the theory of epigenesis seemed to have won the game. However, after 1850, and for just over a century, a cascade of new discoveries tipped again the balance towards the theory of preformation. Let us see what they were:
  1. The existence of a nucleus within animal and plant cells.
  2. The confirmation that the nuclei of the male and female gametes are fused during fertilization. This put an end to spermism and ovism and made it clear that the new being begins in the zygote.
  3. The confirmation that certain structures (the chromosomes) appear during cell reproduction inside the nucleus of the cell, which seem to play a very important role. It was also found that in the chromosomal endowment of the zygote, half of the chromosomes come from the father and the other half from the mother.
  4. A new science (Genetics) was originated in the experiments of Thomas Hunt Morgan, who showed that the chromosomes are linked to Mendelian inheritance.
  5. The works of Oswald Avery, who showed that DNA, a nucleic acid that appears in chromosomes, is the basis of Mendelian inheritance.
  6. The discovery of the structure of DNA (a double helix), made in the early 1950’s by Francis Crick, James Watson and Rosalind Franklin.
  7. The deciphering of the genetic code, which took place during the 1950s and the 1960s.

Thursday, April 5, 2018

Preformation and epigenesis

The history of the evolution of scientific theories about embryonic life (the origin of living beings) is very curious. I will try to summarize it in a couple of posts.
Throughout the history of science, the problem of the embryonic development of multicellular organisms has been one of the most arcane mysteries that man has tried to solve. Faced with this problem, two conflicting solutions have essentially been proposed:
         Preformation: During embryonic development there is just a growth of the pre-formed embryo, whose constitution and composition are completely ready-made from its origin. Everything is done from the beginning, whether in the egg, the sperm or the zygote.
         Epigenesis: Embryonic development is a process. Not everything is decided from the beginning; everything happens because something - a vital force, or an external or internal action - forces the embryo to develop in one way, rather than another.

Thursday, March 29, 2018

About the social order

In a comment to the Spanish version of a previous article in this blog, JI Gs wrote this:
All societies have an explicit social order, whether they are fundamentally believers or not in the immaterial; even animal societies, let alone insects, have a strict social order and the immaterial has no need to act to generate it or to maintain it.
I have two considerations to make:
Solitary bee (Megachile) and social bee (Apis)
  • Comparing human societies with insect societies is a false step. The human social order is based on a set of moral rules that has remained fairly constant over time, except in relation to sexual morality (see the appendix to The Abolition of Man by C.S. Lewis). The social order of insects is programmed in their genes and their nervous system. While in the human species it is possible, even frequent, that one or more members of society rebel against one or more rules, or even attempt to overthrow the entire social order, the members of insect societies cannot rebel. In other words, man is conscious and free, insects are not. Any comparison between them is out of place, because they are based on totally different structures.

Thursday, March 22, 2018

Can there be life without the weak interaction?

Beta and neutron decay

On January 30, 2018, the Science News magazine commented on an article recently published in arXiv which states that in a universe without the weak interaction, life would still be possible. When I read the Science News article, I immediately thought of an objection that could ruin both the thesis of the original article and its popularization. The first thing I did was looking up the original article, to see if my objection was mentioned or denied, but there was not a word about it. Next I detailed my objection in a comment in the web version of the Science News article, but so far no one has answered me. However, I think the objection is quite strong, and unless I am answered satisfactorily, in my opinion these articles are discredited.
According to the standard cosmological model and the standard model of particle physics, there are four fundamental interactions or forces in the universe: gravitation, electromagnetic interaction, and the strong and weak interactions, which regulate the work of atoms and elementary particles. In particular, the weak interaction affects all the elementary particles: leptons and hadrons, unlike the strong interaction, which affects only hadrons.

Thursday, March 15, 2018

Dark energy again

Albert Einstein
In a previous article I mentioned that Einstein introduced a third term in the right side of his cosmological equation, to force this equation to have as solution a stationary cosmos, that would not expand or contract. The attempt was unsuccessful, for such a cosmos would have been in unstable equilibrium, and the smallest variation would have pushed it to either expanding or contracting. The term in question depends on a constant (L, the cosmological constant), which we don’t really know what it is.
Einstein's cosmological equation
For most of the twentieth century, it was assumed that the value of the cosmological constant must be zero. In other words, the third term of the Einstein equation would not exist, wouldn’t be necessary. However, in 1998 it was discovered that the universe seems to be expanding rapidly. At least, this seems to be indicated by the study of supernovas in very distant galaxies, about one billion light-years away from us. To explain this discovery, the cosmological constant term was resurrected, but giving it a sign opposite to that proposed by Einstein, so that rather than the expansion being counteracted, it would be accelerated. This proposal has become the standard cosmological model, in which the first term of the equation, which represents the effect of the mass, currently counts as 31%, while the third, that of the cosmological constant, counts as 69%. In this model, the second is assumed to be zero. I leave apart the question that the mass term does not match, so it has been necessary to assume that there is also a dark matter, that we don’t know what it is.

Thursday, March 8, 2018

One hundred years since The Decline of the West

Oswald Spengler
This year it will mark one century since the publication in 1918 of the first volume of the book The Decline of the West, by Oswald Spengler. The second volume was published five years later, in 1923. This book was the first to raise the idea that our famed Western civilization is in decline. What can we say about it, a hundred years later?
The great historian of the twentieth century, Arnold J. Toynbee, agreed with Spengler on his fundamental idea, although not in the details. For Toynbee, Western civilization collapsed in the twentieth century, when the two world wars proved its inability to face new challenges. Of course, for Toynbee, the collapse of a civilization does not mean its disappearance, it does not even prelude it. We still have ahead - according to him - a few centuries of what Toynbee calls the Universal Empire, linked, however, to a certain cultural stagnation.
The first thing we have to notice is: if Spengler actually managed to detect the decadence of our civilization, it means that the decline had begun much earlier. Evolutionary movements, both biological and cultural, are imperceptible at the beginning. When they become visible, they are quite advanced in their development.

Thursday, March 1, 2018

The problem of human intentionality

A few weeks ago I had in another blog a debate that confronted me with three militant atheists who stood for materialist monism, which holds, among other things, that we are determined by our neurons, that consciousness is an irrelevant epiphenomenon and that free will is an illusion. In another post in this blog I have touched on that topic, mentioning the four philosophical theories that try to explain the conscience, one of which is materialist monism.
This is the argument I offered to defend dualism against materialistic monism:
Let’s tackle the problem of human intentionality. When I say: I'm going to lend money to the bank, so I’ll be paid interest, I’m saying that the reason why I’ll lend money to the bank is to get interest. This is the kind of cause that Aristotle called a final cause, because it is the goal toward which my action is directed, something that is located in the future. On the other hand, materialist monism says that the only cause of our actions is in the electric discharges of our neurons. This is what Aristotle called an efficient cause. Therefore, to explain the same phenomenon (my lending money to the bank), we are suggested two different causes: my intention and the sparks in my neurons, this second located in the present, the first in the future. Is this possible?

Wednesday, February 21, 2018

Chaos and catastrophes

Michael Crichton's novel Jurassic Park is an allegation against the unreasonable use of science. In the words of Dr. Ian Malcolm, one of the characters in the book:
Scientists are actually preoccupied with accomplishment. So they are focused on whether they can do something. They never stop to ask if they should do something. They conveniently define such considerations as pointless. If they don't do it, someone else will. Discovery, they believe, is inevitable. So they just try to do it first. That's the ga me in science. Even pure scientific discovery is an aggressive, penetrative act... Discovery is always a rape of the natural world. Always.
This problem arises especially in the scientific field that serves as the basis for Crichton's novel, genetic engineering, which poses many important ethical problems. There are many things that we can already do, or are close to achieving, but should they be done? I will mention a few:

Thursday, February 15, 2018

The star of Bethlehem

Giotto - Adoration of the Magi
Chapter 2 of St. Matthew’s Gospel begins with these words:
After Jesus was born in Bethlehem in Judea, during the time of King Herod, Magi from the east came to Jerusalem and asked, “Where is the one who has been born king of the Jews? We saw his star when it rose and have come to worship him.”
First, a few considerations about this text:
  • Magi is a term with different meanings. Strictly speaking, it was applied to the priests of Mazdayasna, the religion of Zoroaster. Zoroastrian magi were frequently devoted to astrology (the name then given to the science we now call astronomy). So, in a broad sense, the word magi could be applied to anyone who worked in that science. The New Testament does not say that they were kings. That is a later tradition.
  • It will be noted that the text does not say that they were three. They must be at least two, since the term is plural, but later thinkers have discussed whether they were two, three, or even six. The three magi is also a later tradition.
  • It is explicitly stated that King Herod was alive. When did Herod die? Since Emil Schürer (1896) it has been assumed that he died in the year 750 ab Urbe condita (a.U.c., since the founding of Rome), which corresponds to year 4 b.C.e. (before the Christian era). From this, many historians deduced that Jesus Christ must have been born before that date. Therefore Dionysius Exiguus, author of the idea of ​​numbering the years since the birth of Christ, would have made a mistake in assigning the year 754 a.U.c. to his birth. But some modern historians think that Herod could have died in the year 753 a.U.c. (year 1 b.C.e.), and that his sons pushed back the beginning of their own reign, thus causing the discrepancy and leading Emil Schürer to a wrong conclusion. Consequently, the most probable date for the birth of Christ would be between the year 7 b.C.e. and the year 2 b.C.e.

Thursday, February 8, 2018

Scientific questions in Blade Runner

Philip K. Dick's sci-fi novel Do androids dream with electric sheep? was published in 1968 and quickly became a cult book, with many supporters and not a few detractors, among them myself. Fourteen years after its publication, its adaptation to the cinema with the title Blade Runner multiplied the number of its supporters.
In another post in this blog I mentioned that, in my opinion, the film is much better than the novel. When I read the latter, I did not like it. The time has come to explain why. This is the plot:
In a future world, in the year 2019, the advance of technology makes it possible to build androids (replicants in the film), beings of appearance identical to a human being, endowed with intelligence, but who have not been born in the usual way; they have been built. This future society tries to keep replicants segregated, so that they won’t mix with traditional humans. To achieve this, a new profession is invented: the killer of replicants who try to pass themselves off as humans. As soon as they detect a replicant doing this, the destroyer pursues and kills the replicant in cold blood, without a trial.
The above summary can be applied almost equally to the novel and to the film. So far, the argument is interesting, original and attractive. Why then did I say that I did not like the novel, but did like the movie?

Thursday, February 1, 2018

Chance or pseudo-chance?

Gregory Chaitin
In computer programming, certain algorithms (called pseudo-random) generate series of numbers that meet the conditions required by statistics to decide on the randomness of a sequence. These algorithms are used frequently to simulate chance.
However, these algorithms have been designed by someone (the programmer who invented them). In fact, they are not usually random, in the sense that, if they are executed several times in a row, they always give the same results.
We have a similar case with the digits of p. Ten trillion digits of p are currently known, and their number is constantly growing. So far, the digits of p have met all statistical randomization tests. However, it is evident that they cannot be truly random, that they are designed. There are simple algorithms that generate them one after another, in the correct order.
Let us go back to the mental experiment of the previous post in this blog. If intelligent beings were to emerge in an artificial life experiment,
Would these beings be able to distinguish between chance and design as the origin of their own existence?

Thursday, January 25, 2018

Chance or design?

Tree of life
In this context, we must distinguish three things:
  1. The scientific theory of evolution, which is strongly supported by data from other sciences, such as embryology, comparative anatomy, paleontology, biogeography, or molecular biology (DNA analysis).
  2. The claim that evolution is a consequence of pure chance, which is not a scientific theory, but philosophical, although its supporters claim that it is scientific.
  3. The assertion that evolution is an example of design, which is not a scientific theory either, but philosophical. The supporters of intelligent design argue that it is scientific.
To solve this dilemma we would have to answer one of the following questions:
         Is there a way to prove scientifically that evolution is a consequence of chance, rather than design?
         Is there a way to prove scientifically that evolution is a consequence of design, rather than chance?

Thursday, January 18, 2018

How the eye evolved

Let us reason about this problem by answering a few questions.
  1. Which part of the eye is most essential? The answer is obvious: the retina. If light cannot be detected, the remainder of the eye is useless.
  2. Can a retina, on its own, without the rest of the eye, play a useful role? Obviously, yes. Many groups of not too complex animals have ocelli, photo-receptor cells that just react to the presence of light, but cannot form images. Of course, perceiving the presence of light offers advantage against being totally blind. The proof of this: ocelli have appeared independently in at least 40 different animal groups.
  3. What is the next step? We also have traces among current animals. The Planaria is a Platyhelminth (flatworm) whose ocelli are located at the bottom of a concavity in its body. Thanks to this, the Planaria not only detects the presence of light, but also, to some extent, the direction it comes from. It is also obvious that being able to perceive the direction of light provides advantage to those who can, against those who cannot.

Thursday, January 11, 2018

The eye as an argument about evolution

Schematic diagram of the human eye
The vertebrate eye consists of five parts: cornea (a transparent insulating layer); aqueous humor; crystalline lens (a lens surrounded by muscles that make it possible to achieve a variable focal length); vitreous humor; and retina. The light passes through the cornea and the aqueous humor, is focused by the lens, goes through the vitreous humor and impacts on the nerve cells of the retina, which generate electric signals that the optic nerve transmits to the brain, which forms from them an image of the external world, where the light rays came from. The brain even turns the image around, as it is inverted when projected on the retina.
The complex structure of the eye has always been a problem for evolutionists, and an argument for those opposed to the theory of evolution. Darwin, in Chapter 6 of The Origin of Species, whose title is significant (Difficulties of the theory) dealt with the problem of the evolution of the eye in the following words:

Thursday, January 4, 2018

What happened to the predictions for 2017?

At the end of every year, many predictions are made about the following year. This applies especially to politics and the technological field. In this blog we are not interested in politics, so we’ll talk a little about technological predictions. What happened to those that were made for 2017 near the end of 2016? Have they been fulfilled?
This question is difficult to answer satisfactorily (with a yes or no), for those who make predictions usually do them on purpose in an ambiguous way, so the next year they’ll be able to say that they were right. For instance: