People are getting taller, fatter and living longer than ever before in history. And all these changes have taken place over the past century, scientists say. However, this is not only about evolution, as one century is not enough for such changes.
Scientists believe that most of the transformations that have occurred over this period of time are the body's response to changes in conditions, such as improved nutrition, health and hygiene. Here are the main changes that have happened to people over the past century.
Increased human height
The latest study showed that people in developed countries have become taller, and the highest average height in the world - 1.85 cm - is observed in the Netherlands. Although Americans were the tallest people in the world during World War II (1.77 cm), growth rates had stalled by the end of the 20th century.
And while average growth has increased in many countries, it has not been uniform. In some countries plagued by disease, war and other problems, the average height has declined from time to time.
Researchers believe that this suggests that negative factors such as hunger or epidemics affect the next generation, and it takes about 5 generations to overcome these factors.
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According to recent research, the relationship between growth and quality of life has been identified, and tall people are perceived as more intelligent and influential.
People are getting fatter
Since the 1970s, researchers have studied the growth dynamics of Mayan children and their families in Guatemala, Mexico and the United States. When the Mayans moved to the United States, they were 11.4 cm taller than their peers in Guatemala and Mexico. However, their weight also increased and they were more likely to be obese.
There is also a trend towards weight gain worldwide. So in 2013, 29 percent of the world's population was overweight or obese.
Why people get fatter is a subject of scientific controversy. Some researchers believe that overeating and lack of physical activity are to blame. But there is also a theory that genetics play a role here, as well as viruses that have been associated with obesity. Contrary to popular belief, many studies have found a link between being overweight and poverty.
Some researchers speculate that this trend is related to epigenetics or inherited changes that affect how the body stores excess energy from food.
For example, if your mother and grandmother went through hard times, this is passed on to future generations, and when times are good, the body tries to store extra energy in the form of fat.
Early puberty
In many countries, children start to mature earlier, especially girls. Many studies have shown that the age at which girls reach puberty has decreased over the past half century.
For example, a study in the United States showed that the age of menarche dropped by 0.3 years per decade from the mid-1800s, when the first menstruation occurred at age 17, until the 1960s.
Research also indicates that there is a link between being overweight and early puberty, and girls with high body mass index reach puberty at an earlier age.
This can have negative health consequences, as research has shown that early maturation is associated with the development of hypertension and diabetes later in life.
There are also social consequences. In some cultures, a girl who reaches puberty is considered old enough for marriage, which means she has fewer opportunities to pursue an education or career.
Human longevity and its negative consequences
People are now living longer than ever. According to WHO, life expectancy worldwide has grown from 30 years in the 20th century to 70 years in 2012. Experts predict that the world average life expectancy for women born in 2030 will rise to 85 years.
Increased life expectancy is associated with advances in medicine, improved sanitation and access to clean water.
However, while these factors have reduced the death rate from infectious diseases, the death rate from degenerative diseases such as Alzheimer's disease, heart disease, and cancer have increased.
In other words, people have begun to live longer, but they are dying from other diseases than in the past. The rise in autoimmune diseases such as multiple sclerosis and type 1 diabetes has been linked by some scientists to improved hygiene. That is, when the body is exposed to too few microbes, the immune system overreacts to even the most harmless microbes.
Human development in the future
What will happen to people in the future, given how quickly technology is changing our world?
There is some concern that the future of evolution will be determined by genetic engineering. Bionic implants, nanotechnology and new drugs can extend human life even further.
Some scientists believe that we can achieve immortality through technology in the next 30 years. While this sounds like science fiction, it's clear that humans are advancing rapidly and technology is having a big impact.