Elise Dela Cruz-Talbert

Contributor: Elise Dela Cruz-Talbert, Epidemiology PhDc, Office of Public Health Studies, UH Mānoa.


Email communication with the contributor, Elise Dela Cruz-Talbert, Epidemiology, PhDc

Image Source: http://www.biologydiscussion.com/fertilization/process-and-significance-of-fertilization-5918-words-biology/736

Human Embryo:

Hawaii Life Expectancy:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2693172/ (Table 1)

My freshman year of college, the scientists were in the throes of sequencing the human genome for the first time with the Human Genome Project. The idea was that mapping the human genome could help understand the unique functions of different genes and especially genetic causes of diseases.

The science seemed so possible, so useful, so fascinating. So I set out to study biology with a focus on genetics and development. Genetics is not such a mysterious science anymore and indeed the topics of gene therapy, gene modification, and whether we are products of our genetics verse the environment –are common. In those first years, biology explained so much for me, it brought some order to nature, even when human nature seemed chaotic.

Let’s take fertilization and human development. During heterosexual sex, male ejaculation normally sends at least 40 million sperms, on an epic journey to find an egg. Milliions will perish on the way due to acidic and mucus coated environment, so that only about10,000 reach the fallopian tube, where depending on timing of ovulation, an egg might be waiting. Then when a sperm gets to the egg, his membrane (outer coating) fuses proteins on the surface of the egg, triggering the release of a little enzymes meant to help get the sperm through to the egg. But the first sperm is not the winner. There is a layer of cells around the egg, called the zona pellucida. It can take around 100 sperm, each digging a little through wall, before one finally makes contact and sends its genetic material in the egg. When that sperm enters, calcium ions harden the wall of the egg so that no other sperm can enter.

The genetic material from the sperm and the genetic material from the egg come together. That fertilized egg, that one cell, contains all the information, all the genetic material for an entire human. It will grow, divide many times, and form a ball, and organize itself into an embryo and the 300 trillion cells of the human body. And that human will have a random combination of genes from both parents, which came from their parents, which came from their parents and so on. Science has helped us to know so much more about this process, but not why.

Genetics has also not provided solutions for many of the diseases that cause high rates of diseases in humans. It’s important, but our environments, our life styles, choices, and opportunities do make a big impact. The field of Public Health has the challenge of encouraging people to make healthy choices in the context of their lives, their genes, their culture.

Life expectancy rates for the state of Hawaii point to some challenges. Hawaiians and Samoans have the shortest life spans, while Chinese and Japanese have the longest, with a difference of about a decade between the former and latter ethnicities. Are these differences explained simply genetics? Culture? Poverty?   Racisms? Colonization?

The answer to this is certainly complicated, as individuals are complicated…each a certain complicated miracle.

–Elise Dela Cruz-Talbert