Dr. Yusuf 'Izz Uddeen explains this topic as follows:

"Among the amazing things which all living beings have in common is the ability to multiply, to produce offspring which will ensure the continuation of the species and that it will not become extinct.

The act of reproducing is accomplished by different means in different creatures, but they all reach the intended goal. Bacteria (which are kinds of plants) multiply, as do all other kinds of plants and animals, according to their various levels. From a mathematical point of view, it is impossible that a series of accidental events could have led to the appearance of males and females in thousands of plants and animals to serve a specific purpose, which is the production of offspring to protect the species from extinction.

There are some plants and animals in which there is no distinction between males and females, but they still multiply and produce offspring. Tiny primitive animals such as the amoeba, which lives in water and whose body consists of a single cell, multiply in an amazing fashion. One amoeba divides into two parts, each of which turns into an amoeba. The creatures formed by this cell division divide into two in turn, and so on. This happens when the circumstances of life are suitable.

But if this creature feels any sense of danger, it creates a bubble around itself and divides into two, and into tens of new creatures inside that bubble, so as to make up for the time which it may otherwise have wasted inside the bubble waiting for circumstances to return to normal.

Multiplication by division occurs in numerous other primitive animals apart from the amoeba, such as the animal called a paramecium, which also lives in water and also multiplies by dividing into two in suitable circumstances, like the amoeba. But from time to time when it needs to renew its energy and vitality, it resorts to another kind of reproduction which is very complicated. It mobilizes its nucleus (and every cell has a nucleus, as is well known) to make every cell divide into four, instead of only two.

In animals which are superior to these primitive animals, if circumstances prevent females from mating with males in order to produce offspring, the animal becomes both male and female, i.e., it becomes a hermaphrodite, with both female and male reproductive organs side by side in its body. Thus it is able to produce offspring without having to wait for the opportunity for the two sexes to come together. This happens, for example, in the case of the liver-worm which lives in the ducts of the gall-bladder of some animals, where it is very difficult for them to move about in this constricted space to seek out the other sex. At the same time, if it so happens that two of these worms are able to fertilize one another, one will become like the female and the other will become like the male.

The notion that millions of accidents happened at the same time and served a specific, common goal in many different species and in many different ways is something that is inconceivable by scientific and mathematical standards. In this case we have no option but to accept the existence of an active, creative power behind all of this. From the time of the first appearance of mammals on earth, the female was equipped to produce milk which would guarantee nourishment for the young as soon as they emerged from the mother's womb. If these mammary glands, which protrude from the mother's body, had not existed from the first moment that mammals appeared, the young would have had no chance to grow and survive. This is something that has been decreed and decided from the beginning, and is not subject to trial and error because there is no room for even the slightest mistake.

Can any rational person imagine that this provision of food for the newborn would happen as the result of blind chance? The milk of female mammals, in addition to providing nourishment, has also been found to contain materials which give the newborn immunity against diseases until it grows stronger and its body is able to protect itself. All efforts to manufacture the milk needed to nourish newborns have failed to produce milk that has the same characteristics as the milk that Allah has supplied to the female."

Dr. Yusuf also tells us about the sexual instinct and its importance and impact. He says:

"Among the things that puzzle scientists is the sexual instinct, which makes males attracted to females and vice versa.

The sexual instinct is the strongest of instincts, because it is the most important for ensuring the survival of the species and protecting it from extinction. The main purpose in life for some animals is to mate and perpetuate the species, and they die immediately after that.

The complete life cycle of the insect known as the may-fly is no more than a few days. During its entire life cycle it does not eat, because it is not equipped with a mouth at all. Its primary role during this short period of time is to mate and produce offspring. The mother dies as soon as she has fulfilled her role, and the father dies likewise."

In his articles in Al-Ahraam newspaper, Dr. Yusuf discusses the characteristic which Allah (), has bestowed upon His creatures, whereby they are able to make up for any part of their bodies that they lose:

"Among the other amazing features that we see in all animals and plants is the ability to make up for missing body parts. We find this ability, to one degree or another, in different living beings.

In many animals such as that which is called the hydra, we find an amazing feature which science can only describe, but it cannot explain. This animal lives in water and takes the form of a tube which is no more than a few millimeters in length. The tube is closed at the bottom and is open at the top. This opening serves as a mouth to take in food, and it is also used to expel waste matter. Around this mouth there are a number of hollow tentacles which are connected to the hollow tube inside its body.

If we cut this animal into two, an upper half and a lower half, we find that some cells in each half multiply to complete the part that is missing, and the result is two animals which look like the original. But it does not stop there. If we cut the animal into several pieces, each piece will grow and will make up the missing parts, and will become a perfectly formed animal.

The walls of the hydra's body are composed of two layers of cells, an outer layer and an inner layer which surrounds the hollow space inside its body. In each layer there are different types of cells, each of which performs a specific function. Most of the cells in the outer layer serve to protect the body, whilst the main function of the inner cells is to digest the food which the animal swallows through its mouth opening.

If we turn this animal inside-out, like a sock, so that the outer cells are on the inside surrounding its hollow centre, and the cells which were inside are now on the outside, what happens? The scientists who carried out this experiment discovered that the cells which are now on the outside migrate towards the inside, and the cells which are now on the inside migrate towards the outside, so that the animal will go back to the way it was. If this did not happen, the animal would die, because the cells which surround its hollow middle have to be digestive cells which can process the food in the animal's hollow middle. At the same time, the cells which are on the outside have to be protective cells which can defend the animal's body.

If an earthworm is cut in half, each half will grow, and will make up for the missing parts.

In other animals, such as the shrimp and others, if it loses one of its legs, it grows a new leg to replace the lost limb. If the wall gecko senses danger or a person or animal grabs it by the tail, it will detach that tail from its body and escape from the danger, and it grows a new tail.

If we humans cut ourselves when shaving or for any other reason, new cells form to replace the cells that are lost. If that did not happen, it would be impossible to perform surgery.

If we break a bone, new cells form and the break heals.

This could not have happened as the result of an accident. It has to be the result of a plan aimed at a specific goal, which is the preservation of the life of the individual. It is controlled by inner forces residing in the animal, the nature of which is not fully understood by science. It is a force which Allah has created in animals, but the animal knows nothing of it and does not know what it is doing."