Neanderthals are the reasons for diseases in the world today according to BBC News.
A study in the science journal Nature says that the creatures had genes similar to type 2 diabetes, Chron's disease, and smoking addiction according to the study BBC News reported.
Long-term depression, lupus, and billary cirrhosis are also associated to the human species BBC News reported.
"We found evidence that Neanderthal skin genes made Europeans and East Asians more evolutionarily fit," Benjamin Vernot, of the University of Washington told BBC news. Vernot is also one of the authors of a study in Science Journal.
Neanderthals reigned areas from Britain to Siberia until becoming extinct 30,000 years ago BBC reported. Man species were also growing in population in an African homeland.
"It's tempting to think that Neanderthals were already adapted to the non-African environment and provided this genetic benefit to (modern) humans," David Reich, a professor from at Harvard Medical School told BBC News.
Reich is also one of the authors in the journal.
"It tells us that when Neanderthals and modern humans met and mixed, they were at the very edge of being biologically compatible," Reich told BBC News.
"I think what we're seeing to a large extent is the dying remains of this extinct genome as it is slowly purged from the human population," Joshua Akey of the University of Washington told BBC News.
"Admixture happened relatively recently in evolutionary terms, so you wouldn't expect all the Neanderthal DNA to have been washed away by this point," Akey told BBC News.
Scientists found certain sets of chromosomes did not contain Neanderal DNA in what is believed to be because of changes in offspring.
"We find that there are large regions of the genome where most modern humans carry little or no Neanderthal ancestry," Sriram Sankararaman, a post-doctoral fellow in the Department of genetics at Harvard Medical School told BBC News.
