It is said that 6,000 years ago, there were only 20 million people on Earth; after 5,000 years, the population increased to 400 million; and in the last 500 years, the population growth has suddenly accelerated, now exceeding 7 billion. In the 1950s, the average life expectancy of Chinese people was only 50 years, but by the early 21st century, it had exceeded 70 years. There are many reasons for the increase in population and the extension of life expectancy, and medicine has played a significant role in this regard.
In the 14th century, a terrifying disease swept across Europe, causing the deaths of countless people, which was known as the "Black Death" (plague). In the 19th century, another terrifying disease emerged, causing patients to vomit and diarrhea until death, which was known as "cholera". Tuberculosis, a disease that had plagued humanity for centuries, was once an incurable disease. Fortunately, French scientist Pasteur and German microbiologist Koch later discovered that these diseases were caused by bacteria. With the invention of sulfa drugs and antibiotics, which are the nemeses of bacteria, infectious diseases were eventually controlled. While bacterial diseases were controlled, viral diseases emerged. Nearly 100 million Chinese people are carriers of the hepatitis B virus. Fortunately, advances in medicine have enabled people to prevent it with vaccines and control it with medication.
To understand human medical achievements, one can look at the Nobel Prizes over the past century. These awards annually recognize inventions and discoveries that benefit humanity: In 1901, Röntgen discovered X-rays, which now enable the detection of even pea-sized tumors in the body, thanks to his work. Today, diphtheria and tetanus no longer terrify people, as Behring invented serum therapy, for which he and Röntgen were awarded the 1901 Nobel Prizes in Physiology or Medicine and Physics, respectively. In 1923, the Nobel Prize in Physiology or Medicine was awarded to the discoverers of insulin; in 1924, the inventors of the electrocardiogram, which is still in use today, were among the winners; subsequently, the inventors of sulfa drugs, penicillin, and streptomycin, which helped control infectious diseases, also received Nobel Prizes in Physiology or Medicine; and the creators of the polio vaccine, which led to the development of corresponding vaccines, also won the Nobel Prize in Physiology or Medicine. The invention of the catheter for checking coronary heart disease was also honored with a Nobel Prize in Physiology or Medicine.
In the 21st century, biologists and medical scientists have begun to focus on new research fields. Why does a fertilized egg develop into a complete baby with a heart, lungs, head, and feet over the course of 10 months? Research on this most primitive stem cell suggests that