Who first discovered America?
Answering the question "Who discovered America first?" will be a continuous struggle. History is never certain. While we can know dates and names and events, we can never be certain when a "first" happened. This is because archaeology is continually revealing new evidence on our origins and historical events.
For a very long time, everyone assumed that Columbus had first discovered America. Yet in recent years, the very term "discovery" has come under fire. There were people in America before Columbus. More importantly, there are ancient texts that refer to various explorers who reached America from Europe (and possibly China) before Columbus.
So who really discovered America? To answer this question, we need to go back in time...
Columbus sailed the ocean blue. In the year 1492 AD, Columbus "discovered" America. Well, not really. He actually bumped into a giant land mass that had been visited by Europeans (and possibly others) before. It also happened to be inhabited, at the time, by anywhere from 2 million to 112 million people. The population estimates are still under debate by scholars, such as Henry Dobyns and Douglas Ubelaker. However, what is certain is that Columbus - and all the fabled tellings of his "discovery" - was not the first time to set foot on the soil of the Americas.
Were Africans first?
There is some evidence of African contact in pre-Columbian civilizations. In Mexico, stone head portraits of basalt on the eastern coast bear a striking resemblance to African peoples. Arab sources from the eighth century also detail contact between Africans and the Americas.
Additionally, Portuguese sources speak of migrations from West Africa between 1311 and 1460 CE. These sources tell us that Africans (and most likely Arabs as well, who inhabited the northwestern portions of Africa as well) had sailed to Haiti, Panama, and possibly Brazil. Columbus, after his first contact, encountered the Arawaks who told him of obtaining guanine spear points from black traders that came from the south and east. Captain Balboa provided further evidence in his account of natives who had black slaves.
Sailing to Vinland
Ah, the Vikings. Fabled seamen and storytellers. In the Nordic sagas, the Vikings have recounted the tale of Erik the Red and Leif Eriksson (son of Erik the Red) who sailed to a land called "Vinland." Little credit had been given to the reality of this story until archaeological discoveries started yielding surprising information.
In 1362, the Kensington Stone was inscribed, referring to an expedition of Norweigens and Goths who reached southwestern Minnesota in 1362. The stone was discovered in 1898 by a Swedish-America farmer near Kensington, Minnesota. Scholars initially labeled this stone as a fraud, but research done by H. R. Holad in 1907 showed that the inscription could be from the 1300s based upon its word forms and numerals. This evidence was further corroborated when an account dating to 1355 by a king of Sweden/Norway referred to a western settlement ("Vest Bygd") in Greenland that helped colonists in Vinland.
Other accounts - notably of Gudrid, found in The Far Traveler - also mention Vinland. Gudrid, as a side note, is thought to be the first European woman to have a baby in America.
The sagas refer to Leif Eriksson making landfall in Vinland as early as 1000 CE and his father, Erik the Red, making landfall about 984 CE. They refer to Native Americans as "Skraelings" in the sagas. Most of these come from Nordic folklore, but many other aspects of their folklore have been proven true in recent decades. Is it plausible that the Vikings could have reached America? Yes, their ships were fully capable of such a voyage.
But is there hard evidence? Actually, yes. A Viking-era settlement, bearing striking resemblances to Viking settlements in Scandinavian countries, was found at L'Anse aux Meadows in Newfoundland, Canada, in 1960. Since then, digs at the site have revealed over 300 years of sporadic contact between the Vikings and Native American peoples, concentrated primarily in the Canadian Arctic. A good series of articles, with artifacts, can be found at this Smithsonian website, further detailing what may have occurred at the settlements.
Irish Monks and Giant Sea Turtles
The Vikings, unfortunately, were not first.
St. Brendan, an Irish monk, claimed in his writings to have found "enchanted islands" far out in the Atlantic around 400 CE. Most legends claim that St. Brendan traveled across the Atlantic on the back of a sea turtle, but ancient descriptions claim that he traveled in a tiny currach (a traditional Irish boat of wood and leather). One reason St. Brendan rose to popularity was due to the account of his travels in the 9th century The Voyage of St. Brendan, a Latin book full of fantastic tales about his journey.
No hard evidence of his visit has been found, though it is plausible that ship technology of the time might have reached Nordic settlements on Iceland or Greenland. This was tested in 1976 by historian Tim Severin, who built a traditional currach named Brendan and attempted to sail to North America from Ireland. Severin was successful.
Unfortunately, it is highly unlikely that St. Brendan's tale is true. It is more plausible that the accounts of St. Brendan reflect stories of visits to the Americas, since these stories were written down centuries after they had occurred (and likely had been passed down orally, and thus may have been elaborated with each retelling). However, St. Brendan's story did have a direct effect on the search for America: his tale was used by Christopher Columbus as a reference to support his assertion that lands were reachable across the Atlantic.
Cleopatra and the Chinese
In 600 BCE, there is the possibility that Phoenicians or Egyptians may have visited the Americas. There is speculation that Egyptian technology could have travelled as far the Canary Islands (off the coast of Spain) or Ireland, though it has been untested (to date) as to whether their technology could have reached the Americas. However, Negroid and Caucasoid likenesses in sculpture and ceramics of the Americas, as well as some accounts in Arab history, suggest that contact may have occurred.
Additionally, in 1000 BCE, it is thought that the Chinese may have reached Central America. The evidence is of fairly low quality. However, some Chinese legends and cultural similarities exist between Native Americans and the Chinese. No hard evidence has been found, to date. (Additionally, evidence has been found that the Chinese may have reached America in 1421 CE - 70 years before Columbus.)
Walking on Thin Ice
However, if we are asking who truly "discovered" America - the first person to set foot on the soil of any of the American continents - then we must venture into prehistory. In the Pleistocene era, the Cordilleran and Laurentide ice sheets formed a narrow corridor and land bridge between Russia and what is now Alaska.
So far, archaeological evidence suggests that the first people - who would become the "first Americans" - walked this land bridge and through the corridor into North America. Traveling south, these peoples would have encountered northern deciduous forests of oak, hickory, and beech lining what is now the Gulf Coast. These migrations took place over long periods of time, as the ice sheets opened and closed the corridor.
But who were these people? Most likely, they were groups from Asia. In order to find out, paleoanthropologists utilize many different methods: language, dental records, and mitochondrial DNA testing. There are some debates between these methods, revealing that the "first Americas" most likely spoke languages of the Amerind family, had dental records that matched those of Southwest Asians (the Sundadont family), but whose mitochondrial DNA had very different characteristics than those of modern Asians (suggesting that the "split" between modern Asians and Native Americans occurred at least 21,000 years ago).
What we do know for certain, however, is that after the ice sheets melted and the Ice Age came to an end, those who had migrated to the Americas - whether by foot or, possibly, by boat - became relatively isolated from developments in the rest of the world. This isolation resulted in a loss of immunity to diseases, which would come back to haunt the natives when Europe came calling.