Los científicos han probado que los humanos son los culpables
 

Scientifics have proved that humans are the guilty ones.
True?

Not true, but grammatically correct, except for scientists

Grammatically correct. Depending on context a better translation may be:

"Scientists have proved that humans are at fault."

Lots of people say "have proved" but I really prefer have proven. If you are a stickler for grammar, have proven is the right choice, but I feel the languate is shifting in this case. I may say have proved when I speak, but not when I write.

My initial reaction was "...humans are to blame". It stays very close to the Spanish but sounds more idiomatic to me than "the guilty ones". Another option, which would be technically correct but possibly doesn't have the right connotations, is "...humans are the culprits".

I´m afraid I must challenge this. Middle English developed two distinct infinitives from Old French prover, (L. probare), namely proven and preven. In standard English, prove alone survives with past part. proved, but in Scotland and some northern dialects, the pattern preve survived, with past part. proven. In Scottish law, the verdict not proven is a central concept. In the rest of the UK, the form proven is occasionally used beside proved. :)

The past participles 'proved' and 'proven' are both acceptable in American English. Which one you choose to make your own may be largely based on what others around you say.

http://english-grammar-mistakes.blog...vs-proven.html

Here's a good explanation. It mentions the obvious to English speakers
that the word proven must be used if it takes the role of an adjective.
As Rusty and I have written, as past participles proved and proven are often interchangable. The interesting point made is, according to the blog, proved is the preferred past participle in British English while proven is preferred in North America.

Scientist have proven (proved) that humans are to blame.

I would like to know of what we have been found guilty, and what the penalties are likely to be.

In any case, it wasn't me, sir.

My guess is global warming, and if so, you are to blame, as am I. :)