Astrology assumes that the place and time of an individual's birth has an effect on the life of the person concerned. Generally, I think that's true; not because of an alignment of the planets, but more general social and developmental factors. In the days before central heating, a child born in late spring (May, early June) was not challenged by cold and damp in the first four or five months of life. So we have a nice warm baby whose mother is eating food from the garden during the summer months and is nicely nourished herself.

Think of the little lambs gamboling in the fields, born in early spring. Mammals with a yearly fertility cycle tend to have infants born in early spring. Little lambs have nice wooly coats, unlike little humans, so temperature is not quite as important.  But little lambs do need nice grass to move on to after suckling. So there's a slightly different advantage there. Food supply.

If we assume the human baby is weaned at about a year, the child still has an advantage: full garden with fresh veg easy to mash up. (Incidentally, there is no 'natural weaning time'. It depends on availability and quality of weaning foods and mother's work role. Agriculturalists that rely on yams for subsistence have extended periods of breast feeding. Yams are a lousy weaning food.)

So, in Northern Temperate regions I would expect a child born in May to have a head start in terms of physical development. A non-believer who crunched a bunch of numbers to see if there was any correlation between star sign and occupation was surprised to find a small statistically significant correlation between Taurus (April 20 - May 19) and professional athletes - the only such correlation. The astrological symbol of Taurus is the bull and the description of those born under the sign mention physical strength, stubbornness and single mindedness. Not a bad description of qualities useful for a professional athlete, I think. These are not, of course, qualities restricted to Taurus and the statistical correlation is small.

It would be interesting to look at the Southern hemisphere at the same latitude and see what star sign, if any, correlated with professional athletes.

I imagine all those people who developed different systems of astrology, looking at human beings and seeing similarity and difference: how do you explain it? They mapped the changing night skies and saw that as an explanation. Darwin, essentially, looked at the same thing: change through time, similarity and diversity. I think Darwin is much more satisfactory in his explanations but there's a kind of kinship: those old Mayans and Chaldeans, looking at the night sky and paying attention to what they saw and trying to explain it. Curious folk, that looked and saw. Astrology falls into the rough category of 'science' rather than 'religion'. It's wrong, but that's irrelevant. (Science, unlike religion, is perfectly cheerful at being wrong; individual scientists are another matter. Like most folk, they get pissed off at being told they're wrong unlike priests who either pity or damn the mistaken. But we're talking kinds of belief here, not people.)

Back to my re-interpretation of astrology. When and where a child is born influences the life of the child. The human development cycle unfolds within a social, cultural, ecological and physical context which is based, in part, on the rotation of the earth around the sun.  A bit broad, admittedly; let's look at something specific.

Historically, the school year corresponds to the agricultural year. Children went to school in the winter because they weren't needed on the farm. In some agricultural districts, there was a spring break to accommodate planting. In North America and Europe, children were off during the summer. As education became more widespread and people more numerous, schools were divided into same age classes. Six year olds started Grade 1. Here birth date becomes important.

It's convenient to have one entry period - convenient for the teacher and school system, not children. Let's assume a September 1 cut off date. A child born on August 31 starts first grade at the same time as a child born September 1 - there's a one year difference in actual age between the children. At six, this is a huge difference. I would expect children born in September to be more successful in the early primary grades than children born in August. I don't think there would be a great difference - there are entirely too many variables, not least that stages of development are universal but ages of development are not - but I think it would be significant and it's an hypothesis fairly easily checked -- and probably has been.

Using Google, I found an article: "Do School Entry Laws Affect Educational Attainment and Labor Market Outcomes?" by Carlos Dobkin and Fernando Ferreira. There's support for the position that entry age affects educational achievement. They look at additional factors that modify the impact of differential age on starting school. The web address for the article:

http://people.ucsc.edu/~cdobkin/Papers/School_Entry.pdf

Let's abandon the individual and look long term conditions that effect masses of people; say all those born in a five or ten year span.  My generation, that born between about 1940 and 1945, again in North America and the UK, was a lucky generation. If we look at health, educational achievement, income, we did well. Most of us expected to have pensions and well-funded old ages; some of us will. We've done well enough to think that we might have been born under a lucky star.

There's another biological similarity: foxes and rabbits. An excess of rabbits results in a fine fat fox population that increases. The rabbit population, as a consequence, decreases. Foxes go hungry and fewer are born and fewer survive. Rabbits do well as a result. It's a tidy little cycle. It ignores fox ingenuity, rabbit stupidity, garbage cans and myxomatosis but remains a standard example in high school biology classes.

My generation had an artificially depressed population because of WWII. The men came home and made up for lost years: a big population bulge; lots of jobs building houses, teaching children and selling cars to the generation that followed.

There was more that made us lucky. Our parents, home from the war, had assorted GI benefits. Cheap mortgages, university fees and living expenses paid. Women left their jobs (not always willingly) as men left the armed forces and took the jobs back. Unions were strong and a blue collar worker could support his family on one income. The family had major health care as a benefit of working - another union innovation.  As a result of the Great Depression, banks and investment firms were regulated -- the cycles of boom and bust typical of capitalism were smoothed. We still had recessions, but nothing like the Great Depression our grandparents survived.

The United Kingdom had been through a Great War, and, unlike the last Great War, they looked at the rubble that formed large parts of the urban landscape and wanted a country 'fit for heroes'. They didn't just rebuild the bombed out houses, they established a safety net for the feckless, the unlucky, the disabled, those temporarily unemployed. There was a more or less general agreement that in a decent country people don't starve to death because they can't afford food and one-legged soldiers deserve better than a life sitting on the sidewalk selling pencils. The Welfare State was born. Most importantly, the National Health Service was established.

Like health care, educational access was more available to my generation than to our parents. In the UK, more people, and a different class of people, went to university and were the first members of their family to do so. We looked forward to continuing progress: we did better than our parents, our children will be better off than we are, on and on and on.

That didn't happen. It is fairly evident in 2009 that we can forget continuous progress. While the specific, actual historical contexts are very different, there is a broad historical cyclic action tied to relative population growth and technological change. Today, we have a world with too many people, an economy that relies on energy produced by diminishing fossil fuels, and climate change accelerated and in part produced by human activity: population plus technology results in change. This time, not for the better.

Mayan astrologers (who are equally astronomers) have a calendar that ends in 2012. Interesting. Will Earth shake itself like a dog tired of fleas and get rid of us? Metaphorically, sounds about right about to me. Not, however, in 2012. My generation continues its lucky life: we're all right, Jack. The children are in power now and  dealing with current social and political upheavals. (There is, I admit a niggling fear that 'dealing with current problems’ involves health care rationing, cutting pensions, and allocating scarce resources to the young. It's rabbits and foxes, again, with adjacent generations competing. Could be worse: they could decide to put us down. Perhaps our children can look forward to that.) The real crunch, and the last chance to prevent human beings from becoming a threatened species, will come for the grandchildren, about 2050.

And, as Shakespeare said, "The fault, dear Brutus, lies not in our stars but in ourselves...."