Best science and medical stories of 2015

2015 has been full of scientific and technological innovation news from all around the world. From 3-D surgical implants to artificial intelligence, here are some of the scientific achievement stories of this year.

NASA's New Horizons probe capture best images of Pluto

After a very long journey - more than nine years and 4.83 billion kilometers, NASA's New Horizons probe captured the closest view of Pluto on July 14. The fastest spacecraft ever launched, New Horizons reached its closest distance from Pluto, a dwarf planet that is among the furthest known bodies from the sun in our solar system. The spacecraft traveled farther away than any space mission in history to reach its primary target, NASA reported in a press statement. New Horizons became the first spacecraft to visit Pluto and its entourage of moons and so far has returned about 5 percent of the pictures and science data collected in the days leading up to, during and immediately following the July flyby. The images include a view of Pluto backlit by the sun, located more than 3 billion miles away, shining around and through the planet's atmosphere. Analysis showed that there are distinct layers of haze in Pluto's nitrogen, carbon monoxide and methane atmosphere. The haze extends at least 161 kilometers off the surface. "This is our first peek at weather in Pluto's atmosphere," New Horizons scientist Michael Summers, with George Mason University in Fairfax, Virginia, told reporters during a teleconferenced press briefing.

Homo naledi fossil found in South Africa



Scientists in October announced the discovery of this previously unknown species in the human evolutionary linage in a cave northwest of Johannesburg. The new research offers fresh insight into a creature that is providing valuable clues about human evolution. The scientists who discovered it call Homo naledi one of the most primitive members of the genus Homo, which includes modern humans. Homo naledi, whose fossils have been retrieved from a South African cave, may have been handy with tools and walked much like a modern human, according to scientists who examined its well-preserved foot and hand bones. Its foot and hand anatomy shared many characteristics with our species but possessed some primitive traits useful for tree climbing, the researchers said. The fossils' age has not been determined. The research appears in the journal Nature Communications.

MIT researchers regain lost memories



Researchers have gained new understanding of the workings of amnesia through research that used light to revive lost memories in mice. Carried out in May, the study published in the U.S. journal Science indicated that memories do in fact remain, but are simply unable to be recollected. "The majority of researchers have favored the storage theory, but we have shown in this paper that this majority theory is probably wrong," researcher Susumu Tonegawa of the Massachusetts Institute of Technology (MIT) said. The study, carried out by researchers at MIT and the Riken Brain Science Institute in Japan, used blue light pulses to stimulate "memory engrams," the neurons that are activated as memories are formed. When these engrams are activated in normal day-to-day life by stimuli such as an image, smell or taste, memories are triggered. The study allowed scientists to separate memory storage mechanisms from those allowing an organism to form and recover the memory, said MIT researcher Tomas Ryan, who coauthored the study.

Turkey becomes associate member of CERN



In May, Turkey became an associate member of CERN, the European Organization for Nuclear Research, one of the world's largest and most respected centers for scientific research. An agreement was signed in 2014 to grant the status to Turkey. According to CERN, Turkish physicists participated in the CHORUS neutrino experiment that is projected to introduce new data on particle physics, astrophysics and cosmology. Associate membership allows Turkey to attend meetings of the CERN Council. Turkish scientists can also become members of the CERN staff and participate in CERN's training and career development programs.

Surgeons implanted 3-D-printed titanium ribs



In September, a Spanish cancer patient received an implant of a 3-D-printed titanium sternum and partial rib cage designed at the Australia-based Commonwealth Scientific and Industrial Research Organization (CSIRO). "This part of the chest is notoriously tricky to recreate with prosthetics due to the complex geometry and design required for each patient. So the patient's surgical team determined that a fully customizable 3-D-printed sternum and rib cage was the best option," stated CSIRO.

Tech giants invests $1 billion in artificial intelligence

Tesla Motors Inc. CEO Elon Musk and other prominent tech executives announced that they are planning to pour $1 billion into a nonprofit aimed at creating artificial intelligence that augments humans' capabilities rather than making them obsolete. The effort announced on Dec. 11, called OpenAI, joins significant investments from companies such as Alphabet Inc.'s Google, Facebook Inc. and Amazon.com Inc., which have used artificial intelligence to sharpen their businesses with services such as facial recognition or language processing. "Our goal is to advance digital intelligence in the way that is most likely to benefit humanity as a whole, unconstrained by a need to generate financial return," a blog post on OpenAI's website said. Earlier in December, British theoretical physicist Stephen Hawking warned that development of artificial intelligence could mean the end of humanity. In an interview with the BBC, the scientist said such technology could rapidly evolve and overtake mankind, a scenario like that envisaged in the "Terminator" movies. "Once humans develop artificial intelligence it would take off on its own, and re-design itself at an ever increasing rate ... Humans, who are limited by slow biological evolution, couldn't compete and would be superseded," Hawking theorized.