Scientists have identified the culprit that brought mankind the scourge known as genital herpes, and it appears it came from an early human ancestor. A new study claims that ancient chimpanzees passed oral herpes genetically to the earliest humans when our lineage split millions of years ago, and we narrowly missed avoiding it altogether.

But unfortunately for us, an early human ancestor was in just the right place to catch HSV-2, and it may be because another hominin species known as Paranthropus boiosei that stood 4 feet tall and had a small brain with a wide face. Bolsei acted as the bridge that allowed genital herpes to jump from primates to humans, scientists believe.

Boisei and Homo erectus lived in Africa somewhere between 1.4 million and 3 million years ago, and they likely interacted at water sources. HSV-2 was in its infancy and was able to spread orally. Chimp bites and scratches could have transferred the virus through sores.

“Two herpes simplex viruses infect primates from unknown evolutionary depths. In modern humans these viruses manifest as cold sores (HSV1) and genital herpes (HSV2),” reads the University of Cambridge statement. “Unlike HSV1, however, the earliest proto-humans did not take HSV2 with them when our ancient lineage split from chimpanzee precursors around 7 million years ago. Humanity dodged the genital herpes bullet – almost. Somewhere between 3 and 1.4 million years ago, HSV2 jumped the species barrier from African apes back into human ancestors – probably through an intermediate hominin species unrelated to humans. Hominin is the zoological ‘tribe’ to which our species belongs.”