This short discussion is directed to furthering questions brought up in the second paragraph as the heart of the title article.

There are about 7000 living languages spoken in the world today, characterized by both exceptional diversity as well as significant similarities. Despite many controversies in the field, many linguistic scholars generally agree on two points (1-8). [1] Language as a system of knowledge is based on genetic mechanisms that create the similarities observed across different languages, culturally specific experience that shapes the particular language acquired, and developmental processes that enable the growth and expression of linguistic knowledge. [2] Also, the neural systems that allow us to acquire and process our knowledge of language are separate from those underlying our ability to communicate.

1 - The 'universality of (human) knowledge' derives from genetic mechanisms which support the physiological registration of some of the various material properties of experience and of the relationals(*1) attaching that materiality.
2 - What (then) are the neural systems that make possible 'the ideation of such entities of experience' and the stringing together or 'deliberation' of such entities into potentially communicable 'knowledge'? -of perhaps even higher sort'?
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(*2) The longer the evolutionary lineage of an animal -in general, the greater its capability for 'learning'. For humans in particular, we generally identify the substance of that learning as 'knowledge'. There is (then) an evolutionary sequence of 'successively higher-order circumstances or situations' that can generally be identified with the evolutionary lineage of 'any discrete animal capable of learning'.

3 - For lineages of primitively first, congregational life (i.e. 'sex') before the evolution of 'self-awareness' or 'communicability with another like me', there are (per Item 2 above) two situations generating 'knowledge and its pre-language communicability':
(a) Life-form alert to threat by another life-form -howl, screech et cetera.
(b) Indirectly calling attention to some on-going phenomenon by 'grunt', sight concentration or touch (more below) -to, in particular, what some other 'prosimian-forward' may be doing.

*4 - For lineages continuing into and beyond such things as 'empathy' and 'awareness of self' then, 'language' (per Item 2) evolves out of 'successively more meaningful grunts' capable of communicating successively higher-order situations 'with another like me':
(c) 'I am doing this thing I happened to learn' -process 'happened upon'.
(d) 'You, there -doing what you are doing -look at what I'm doing' ... directed learning.
(e) 'When this happens, (it looks like) that happens' -the beginnings of deliberate observation.
(f) 'If I do this, then that happens' -the beginnings of deliberated activity.
(g) 'I wonder what happens if I do this' -deliberative capability.

5 - Clearly evolving through the above then is (a) a successively more complex brain of (eventually) successively more physiological convolution and (b) human language itself -which, therefore, cannot have evolved in the absence of 'a congregational someone in evolving communication' -a congregationally sexual someone in particular therefore.

6 - Farther down, the authors say-

The biggest puzzle, however, is why nonhuman animals cannot integrate these computational capacities with their capacity to communicate. The biggest puzzle, however, is why nonhuman animals cannot integrate these computational capacities with their capacity to communicate. The biggest puzzle, however, is why nonhuman animals cannot integrate these computational capacities with their capacity to communicate.