Why do cities and towns tend to develop along rivers like the Rio Grande

the answer is "meiosis ii in the mother".

the procedure of meiosis includes two divisions of the hereditary material. the main division is known as the decrease division – or meiosis i – on the grounds that it lessens the quantity of chromosomes from 46 chromosomes or 2n to 23 chromosomes or (n depicts a solitary chromosome set). in people, the decrease division results in two sperm cells each with 23 chromosomes or an egg cell with 23 chromosomes and one disposed of polar body. the second division – or meiosis ii – is called equational division. the two sperm cells split again creating four sperm cells, each with 23 or n chromosomes. in oogenesis, the egg cell and polar body partition to shape the ovum and two extra polar bodies. along these lines, the posterity are guaranteed to get one portion of the chromosomes from the mother and one half from the dad.

answer; the automatic system because it is a "gut reactor"