The giant forest hog, hylochoerus meinertzhageni, is a quite interesting species of wild pigs. Its measurements are as follows: length of the body - 155 to 180 cm, legth of the tail - 25 to 35 cm, height at the shoulder - 80 to 100 cm, body mass - 100 to 250 kg, diameter of snout disk - up to 13 cm. (Data from this Russian page.)
"Forest Hog social groups consist of one boar, one to four sows and their offspring. Other pigs usually do not allow a boar to join a family group apart from during the mating season. The effect of dominance hierachy was observed for both sexes on the following behaviours: leading the group, protection of the home range, protection of the sows against extra-group males and behaviour in presence of predators. The results reveal that Forest Hogs do not show any hierarchy within the group and all adult animals seem to be responsible for all group members. However, data suggests that there may be an alpha sow, who might be the centre of group coordination."
From "Zur Ökologie und Ethologie des Afrikanischen Riesenwaldschweines" by Sandra Fimpel - a very interesting thesis on a field study of giant forest hogs in Uganda. Even if you don't know German, it's definitely worth it to just look at the many photographs of the subjects of the study (not least the one of the piglet who "playfully nibbles at the boar's testicles" on page 58 ...).
The forest hog groups, as opposed to many other species of wild boars, have a "steady family boar", who is deeply involved in family life and plays with and cares for the piglets. This, Fimpel argues, will give him advantage in the eyes of the sows of the group when facing a strange boar interested in taking over his place, and it also gives him security and social contacts, besides the obvious possibility to pass on his genes.
Fimpel also studied the language of forest hogs, and classified at least 18 different "basic sounds": 5 contact sounds, 4 calling sounds, warning sound, alarm sound, greeting sound, frightened sound, repelling sound, calming sound, sleeping sound, fighting sound and curious sound. Besides that, she once recorded a long, deep "growl" of a boar that was inside some bushes with his group, but the meaning of this sound could not be determined ... I wish samples of the sounds would be available.
See also the chapter on giant forest hogs in the Pigs, Peccaries and Hippos Status Survey and Action Plan by Jean-Pierre d'Huart from IUCN.