Man had created some spell-binding structures even before the advent of technology. In this process of creation, we have got so close to imitating nature that it is hard to tell the difference between what is natural and what is a human innovation.

Some people argue that what is man-made is actually natural and not artificial as man is a part of nature. Keeping that debate aside, let’s delve into this list that will tell you about 10 things that you thought were natural but are actually man-made.

1 Contrary to popular belief, the Amazon basin is not naturally fertile. Indigenous people invented a “superdirt” which could remain fertile for thousands of years and renew and propagate by itself. This covers at least 10% of the Amazon basin today.

When we talk about the Amazon basin, there is a certain picture of a thick, green forest that is rich in flora and fauna in our minds. We cannot imagine that any part of the Amazon basin could actually have been due to a contribution of man.

But there is. Humans have shaped the Amazon rainforest over thousands of years. The natives have played a huge role in creating the diversity that exists today, a fact that was recently revealed some archaeological studies.

Humans have occupied the area for around 13,000 years and have domesticated 8,000 plant varieties that grow today like the Brazil nut, Amazon grape tree, and ice-cream bean tree that are “hyperdominant.”

Another fact that proves that humans have created a part of the Amazon rainforest is the presence of Terra preta or “Amazonian dark earth” that is a very dark, fertile, artificial soil which was made by adding bone, charcoal, and manure to the infertile, common soil that existed in the Amazon basin.

This was created by farming communities between 450 CE and 950 CE and makeup at least 10% of the total area—that would be an area twice the size of Great Britain. This soil renews itself one centimeter a year. (1, 2)

2 Broccoli is a result of selective-breeding of wild cabbage plants that began around the 6th century BCE. This makes it a man-made food and not a natural one—like lemons.

If you had lived 2,000 years ago, you wouldn’t have ever eaten broccoli (some kids would wish that). Horticulturists selectively bred wild cabbage plants that gave rise to broccoli. Wild cabbage plants with larger buds were selected and reproduced over and over again.

This human innovation was grown by farmers in Italy around the 16^th century when it became popular. In 1720, it came to England and much later to America.

And, if you thought that lemons always existed (in life yes, like crop’s not really), you were wrong. Lemons are a cross-breed between sour orange and citron. They are believed to have been first grown in northeast India, northern Burma, or China.

But they were not so popular until the 15^th century when the cultivation of lemons began in Europe. Before that, it was also used as an ornamental plant in the early Islamic gardens. (1, 2)

3 Lake Mead, near the Las Vegas strip, is popular as a recreation area but is not natural. It was made in 1936, formed by the water of the Hoover Dam. The accumulated water from the Hoover Dam caused the evacuation of an entire town whose ruins are visible when the water level goes down.

In 1936, Lake Mead was established as a Boulder Dam Recreation Area and was named after Elwood Mead, the man who was the commissioner of U.S. Reclamation from 1924 to 1936 and in-charge of the planning and construction of Lake Mead.

Located some 24 miles from the Las Vegas strip, Lake Mead has attracted visitors all-year round with a host of recreational activities available for them to indulge in. Many think that the lake is a natural formation, but that is a myth.

Lake Mead is 112 miles long and 532 feet deep. The accumulated water from the Hoover dam in the lake led to the relocation of several communities including the entire town of St. Thomas, Nevada.

When the water level of the lake that provides sustenance to 20 million people drops below normal, the ruins of this town are visible. Since 1983, the lake has never reached its full capacity due to drought issues and the increase in water demand. In 2017, it was at 40% of its capacity. (source)

4 If you thought that earthquakes are always natural disasters, you are wrong. A study identified 730 sites where earthquakes as high as 7.9 on the Richter scale have been caused by human activity in the past 150 years.

Science has given a term to the causing of tremors in the Earth’s crust due to human activity: “induced seismicity.” Usually, the earthquakes that are caused due to human activity of mining, dam building, fracking, etc. are of low magnitude, but some sites have larger magnitude quakes. For example, The Geysers geothermal plant in California has had 17 such events every year of M4 and M3 magnitude from 2004 to 2009.

A study published in the journal of Seismological Research Letters in 2017 pointed out 730 sites where humans have caused earthquakes in the last 150 years with seismicity being as high as 7.9. Many scientists have raised concern as such earthquakes have been on the rise in some regions of the world.

Most natural earthquakes happen on fault lines where the tectonic plates converge. But those that are induced by humans can occur anywhere. Mining accounted for induced earthquakes at 271 sites, and dam building and reservoir impoundment caused multiple high-seismicity earthquakes at 167 sites.

For instance, in 2008, the earthquake in China’s Sichuan was due to the 320 million tons of water collected in the Zipingpu reservoir and took the life of 80,000 people. Nuclear explosions have also been known to trigger earthquakes. (1, 2)

5 It is true that oysters make pearls, but that is left more or less to chance. Today, 99% of the pearls that are found on the worldwide market are cultured. They are grown in controlled conditions by a pearl farmer.

When the rim of the shell of a mollusk is attacked by a parasite or by an aquatic animal, it damages the mantle tissue and a pearl is formed. These “natural pearls” depend on chance, but the demand for pearls in the market is so great that only 1% of it can be met by relying on nature. That is where cultured pearls come into the picture. They make up 99% of the pearls that are in the world market today.

Cultured pearls are grown in controlled conditions by a pearl farmer by using two groups of bivalve mollusks—the saltwater pearl oysters and the freshwater river mussels. The latter is the most effective. A number of shells are collected by the pearl farmers which are then sliced into cubes and then made spherical.

The mantle tissue is harvested from the oysters or mussels and placed into another one with the shell. The second oyster is placed back into the water where, over a period of 2-7 years, they coat the pearl with nacre. Colored pearls are made by adding natural dyes into the mollusk shell. The cultured pearl industry is worth approximately 400 million dollars per anum. (source)