What is life?

PROLOGUE
The Torah states in the Decalogue that Thou Shall Not Murder. This has been accepted as law in the United States. In 1973, the U. S. Supreme Court decided that terminating a pregnancy was not murder and a woman carrying a fetus had the right to terminate that fetus. A few months ago, the Supreme Court decided that the Constitution did not give a woman that freedom and legislation could obviate that choice.
Although the definition of life was not considered in the decision, it becomes a critical issue. Life has been defined by Philosophers, Theologian’s, Legislators, Biologists and, I’m sure, other “experts”. In this presentation I will consider life from the biologic standpoint.

 LIFE
Life takes many forms. We will start with a brief consideration of all life. A living substance must have the ability to metabolize and reproduce. Metabolism involves using an exogenous (from without) source to allow growth, activity and cell division. Plants use sunlight, animals use sources from plants or other animals. We will call substances that are not complete, pre-life. This would include chemicals, such as prions, the substances that cause Mad Cow disease, and viruses. To exist and grow, they use host machinery. We will not consider pre-life or plant life today. We will focus on animals in general and man in particular.

CREATION OF LIFE FROM DNA?
Can biologists today, create life from DNA, as described in the movie, Jurassic Park? The simple answer is no. The starting point would be a complete set of DNA in the correct order. The technology to so assemble DNA in that manner does not exist. Secondly, dinosaur non-DNA, cellular support systems would be necessary. While DNA is very stable, RNA and proteins are not.

THE CELL
All animal life begins as a single cell. Some animals, such as the amoeba, persists as a single cell with the ability to take in substances, to use those substances for energy and to divide into two cells. When the cell divides, each daughter cell becomes a unique individual, able to grow and divide. In more complex animals, when the original undifferentiated cell, a fertilized egg, divides, the daughter cells stay together and differentiate, for example, into muscle cells or nerve cells. Under normal circumstances, these differentiated cells cannot de-differentiate and gain the capability of the fertilized egg to create a new being.

THE LYMPHOCYTE
Let us discuss a differentiated cell called a lymphocyte. As part of the immune system, it just sits in the blood in an apparently inert manner, until called upon to do its specialized job, responding to foreign substances. But man can induce lymphocytes to do extraordinary things. Malignant non-human lymphocytes have been fused with normal human lymphocytes. The hybrid cells, when offered the right environment, can live and reproduce in tissue culture. If the cells are chosen properly, they can produce proteins of therapeutic value. You cannot watch TV without seeing commercials for these products. Are these cell lines, life? They have the ability to metabolize and produce more hybrid cells.

THE EGG AND SPERM
Can we produce life from an egg or a sperm? Life can be created from an egg. An egg has only 23 chromosomes. By inducing DNA duplication without cell division, a cell with the required 46 chromosomes can be created which can then produce life, a technique called parthenogenesis. This will produce only females. Parthenogenesis cannot be induced in sperm.
It was learned that if you took the nucleus out of a lymphocyte of one animal and used it to replace the nucleus of an egg of another animal of the same species, then implanted the altered egg into the uterus of an animal of the same species as the egg donor, an offspring could be produced that was genetically identical to the lymphocyte donor. This technique requires the support system of the egg to nourish the donor DNA. Remember Dolly, the sheep? Therefore, it has been shown that life can be created from a lymphocyte nucleus. Must that lymphocyte be considered life?

CRSPR
For those of you who enjoy science fiction, I recommend Isaacson’s book, The Code Breaker. It’s not fiction. It’s the exciting story of the utilization of Crispr, a technique to alter the genome and cure genetic diseases. Crispr doesn’t create life, but it genetically alters life.

WHEN DOES EMBRYONIC/FETAL LIFE BEGIN?
Some say life begins at fertilization, but some fertilized eggs have fatal genetic flaws and cannot survive. To produce an individual, the uterus must be capable of carrying the fetus to a point of viability. The youngest fetus to survive was born at 21 weeks. By 24 weeks 40 to 60% will survive. By 31 weeks, viability is equal to full term.

BIOLOGIC FACTORS THAT HAVE BEEN USED TO DETERMINE THE BEGINNING OF LIFE
When should a fertilized egg, embryo or fetus be considered alive? At one extreme, a fertilized egg is considered by some to be life. At the other extreme, others believe that life begins only after birth. Intermediate metrics during fetal life have been used, i.e. brain activity and heartbeat. Although we can detect a heartbeat, that doesn’t indicate that the heart is capable of independent function. Although we can detect fetal movement, that doesn’t indicate a functional brain.

SUMMARY OF THE DEFINITION OF LIFE
In summary, life is produced from an egg and sperm. Such a fertilized egg has not produced a viable infant with less than 21 weeks of gestation. Man can create life from an egg, new life from and egg and lymphocyte, genetically alter live by CRISPR, and save a disabled fetus. All life created in these ways require man’s intervention.

WHEN DOES LIFE END?
For millennia, absence of breathing and heartbeat was considered the end of life. Without oxygen and circulation, every part of the body dies, starting with the brain. Life support technology can replace breathing and heartbeat and preserve life in general and the brain in particular. Modern technology uses the EEG to determine brain activity. If there is no EEG activity for a given period of time, function never returns, and the brain and the individual can be considered dead.

Prior to 36 years ago, the time of death was determined by the treating physician. With the advent of life support, the treating physician’s role changed from passive to active when he/she chose to discontinue life support. In fact, physicians were still generally opposed to giving up their prerogative. This reluctance changed when lawsuits started appearing. A particular case occurred at St Louis University. A physician caring for a patient on life support, approached the family stating that the patient was “brain dead” and asked permission to stop life support. The family present agreed, life support was discontinued, and the heart stopped. The next day, another relative arrived and asked how this decision could have been made without his permission. He sued. He did not win, but because of this and many similar cases, the need for a formal definition of brain death became apparent.

In 1986, legislation was drafted by the National Conference of Commissioners on Uniform State Laws with the intention of harmonizing state laws for the purpose of defining death. Because of its relationship to transplantation, the law was called The Uniform Anatomic Gift Act. Each State passed the proposed legislation so that the same law was in effect throughout the Country. It has been updated periodically since.

EPILOGUE
The biologist can identify and have opinions concerning the variables relating to the beginning (and end) of life, and the creation of a new being. Philosophers and Theologians will express their opinions. But the final decision will be made by lawmakers (who we elect) and Judges (who our
legislators appoint).

ADDENDUM
A sidebar to current anti-abortion legislation identifying heartbeat in fetuses as the beginning of life might put in jeopardy The Uniform Anatomic Gift Act which accepts brain death with a beating heart, end of life!!!