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Summer Born Children Are More Likely To Be Healthier Adults

Summer apparently could be the best time to be born. But how true is it? That depends on what traits you consider to be most advantageous. Although a recent study found that baby girls born in June, July, and August develop into healthier women than girls born at other times of the year, past medical research has also linked summer birthdays to those who have less successful career outcomes.

For a recent study, now published in the online journal Heliyon, researchers from Cambridge University in the UK investigated an idea that has fascinated humans: Can a child’s birthday give clues to their future? While we have often looked to the stars for this answer, the Cambridge team went to science instead.


“When you were conceived and born occurs largely ‘at random’ — it’s not affected by social class, your parents’ ages, or their health — so looking for patterns with birth month is a powerful study design to identify influences of the environment before birth,” said lead author Dr. John Perry in a statement.

For their project, the team compared the growth and development of around 450,000 men and women from the UK Biobank study, a major national health resource that provides the data on UK volunteers to shed light on the development of disease. The researchers looked to see how birth month affected the weight, as well as adult height and body mass index. They were also the first to specifically look for a correlation between birth month and when puberty started.

Results revealed that girls born in the summer were slightly heavier at birth, taller as adults, and went through puberty slightly later than those born in winter months which means good health. The team hypothesized differences in the later life health of summer and winter babies may be caused by the amount of sun that their mothers received during their pregnancy — a factor that significantly determines her vitamin D exposure. However, the researchers insisted that, at this point, they are still unsure why this happens.

“We need to understand these mechanisms before our findings can be translated into health benefits,” Perry added.

Previous research, however, has revealed less advantageous effects of summer birthdays. According to a 2012 study published in Economic Letter, individuals born in summer months are the far less likely to hold CEO positions than individuals born in other times of the year. The reason for this was more simple: In many schools, the cut-off date for registration falls between September and January. This leaves those with summer birthdays as the youngest in their grade. Maurice Levi, the study’s co-author said that older children within the same grade tend to do better than the youngest. These career outcomes may be the result of early successes in school.

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Scientists Have Discovered The Body’s “Chemical Calendar”

Scientists have discovered how the body can track each season during the year with a ‘chemical calendar’. The scientists, posting their report in Current Biology, discovered various different cells that could exist in a ‘summer’ or ‘winter’ state.

They used a longer day to switch the cells into summer mode and the complete opposite when the nights draw in to enter winter mode. The annual body clock controls various things in nature including when animals breed and hibernate. Humans may be altering their immune system with the annual clock.

Teams from the Universities of Edinburgh and Manchester analysed the brains of sheep at different points of the year. Within the sheep brains they found a cluster of over 17,000 “calendar cells” within the pituitary gland which sits at the base of the brain releasing hormones that control processes within the body. The research team has said that the cells have a similar “binary system” to a computer that can exist in one of two s

Four_seasonstates producing ‘winter chemicals’ or ‘summer’ ones. And the proportion of the calendar cells in each state changes throughout the year to mark the passage of time.

Prof. Andrew Loudon from the University of Manchester said “It looks like there’s a short period of the year in the middle of winter and the middle of summer when they are all in one state or the other.”

It is still not clear how the body knows when the season is spring or autumn when some of the calendar cells are still in winter mode and other’s are in a summer state. The annual clock is known as the Circannual Rhythm and is the longer-term cousin of the circadian or daily rhythm which keeps you awake at the right time of the day.

This annual pattern triggers stages of nature throughout the year including hibernations, migrations and mating seasons and explains why lambs are always born within the spring season. The daily and the annual body clocks are controlled by light.The sleep hormone melatonin is produced more within the winter season as the days are darker.

Prof. Loudon said “We’ve known for some time that melatonin is critical for these long-term rhythms, but how it works and where it works had not been clear until now.” 

His colleague in this research, Prof. Dave Burt from the University of Edinburgh, added: “The seasonal clock found in sheep is likely to be the same in all vertebrates, or at least contains the same parts. The next step is to understand how our cells record the passage of time.”

Although humans do not have a particular mating season there are signs within the research that we are influenced by the seasons.

An earlier study led by the University of Cambridge showed human genes involved with immunity became active in the cold and winter seasons. In the study they suggested that it could help fight off winter viruses like flu but may make other conditions worsen such as arthritis.