Semitic *gam(a)l- 'camel'

Semitic *gam(a)l- 'camel' is a widespread word which designates the dromedary of SW Asia and North Africa, first domesticated in Arabia before 2,000 BCE¹, and was borrowed into Greek kámēlos and in turn into Latin camēlus. 

This appears to be a Wanderwort which originally designated some wild ungulate of the Eurasian steppes and which is also found in Baltic *kumel-iā̃, Slavic *kobɨ̄lā 'mare' and in Altaic (with metathesis) *kúlme 'a k. of ungulate': Turkic *Kulum 'foal', Mongolian *kulan 'Mongolian wild ass (Equus hemionus hemionus)'², Tungusic *ku(l)ma- 'maral (Siberian stag)/wapiti (Cervus canadensis)' and Japonic *kuáma 'foal, colt' aral' (EDAL 911).

A seemingly related Wanderwort for equids can be found in Caucasian *gwælV (~ -ɫ-) 'horse' (a Nakh-Tsezian isogloss) and which also designates the onager (Equus hemionus): Farsi gur 'Persian onager (Equus hemionus onager)', Hindi khur 'Indian wild ass (Equus hemionus khur)'; IE *g^wold- 'foal, young of an ass' > Sanskrit gardabhá- 'ass'³, Germanic *kult-a- 'colt' (English colt) an Basque zaldi 'horse'⁴, with assibilation of the initial velar. The latter has cognates in the Iberian antroponym formant saldu and Berber a-serdun 'mule'.

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¹ Another species of camel, the Bactrian camel, native to the steppes of Central Asia, was first domesticated before 2,500 BCE.

² Borrowed by Turkic, where it designates the Turkmenian kulan (Equus hemionus kulan).

³ Tocharian B kercapo 'ass, donkey' is likely an early Indo-Arian loanword. See D.A. Adams (1999): A Dictionary of Tocharian B, p. 195-196.

⁴ Although some authors have proposed a link to thieldones 'a breed of Asturian ambling horses' (Pliny) < IE *del- 'to shake' (cfr. English tilt), in my opinion this is semantically unsatisfactory.

Summer and apple: history of a Nostratic Wanderwort

In Greek mythology, Hēméra was the primeval goddness of the day. From this word and Armenian awr 'day', Indo-Europeanists such as Mallory-Adams¹ reconstruct an IE protoform *h₂ēm-ər- '(heat of the) day', which I link to Semitic *ħamm- 'to be hot; warm'², with the voiceless pharyngeal fricative ħ corresponding to "laryngeal" h₂. 

It doesn't take a long stretch of the imagination to devise a derived variant *HVmV-lV/HVmVlV which gave (with metathesis) Nakh-Daghestanian *mhalV/mhanV- 'warm' and IE *mah₂lo- 'apple', with a straightforward semantic drift from 'warm (season)' to 'fruit'. Several IE languages of North Europe (Celtic, Germanic, Balto-Slavic) reflect a protoform *abVl- 'apple' (< *amHVl-?) which is regarded as a Paleo-European substrate loanword by some specialists.⁴

A variant *ʕu-malV/*ʕu-manV would be the origin of Uralic *omena/omVrV 'apple' as well as  Basque udare, udari, madari 'pear'³ (with denasalization and further delabialization), umao (B), umo 'ripe, seasoned'.  This makes sense because the apple tree is originary of Kurdistan, precisely in the area where Nostratic was presumably spoken.

On the other hand, we've got yet another IE variant *sam-/*səm-ro- 'summer'⁴ and Hittite sam(a)lu- 'apple (tree)'.⁶⁵

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¹ J.P. Mallory & Q.D. Adams (2006): The Oxford Introduction to PIE and the PIE World.  

² Also cognate are Hurrian am- 'to burn' and (possibly through an Etruscan intermediate) Latin amāre 'to love', amor 'love'.

³ For example, Theo Vennemann links it to Afrasian *ʔa-bul- 'male genitals', which (in his own words) is "semantically unsatisfactory although phonetically perfect". See T. Vennemann (1998): Andromeda and the Apples of the Hesperides, in Europa Vasconica, Europa Semitica, 591-652.

⁴ The ablaut form *sem- usually quoted in dictionaries isn't attested anywhere.

⁵ Explained by ortodox IE-ists such as Kloekhorst as the result of a "s-mobile".